fetal presentation ultrasound report

Fetal Presentation, Position, and Lie (Including Breech Presentation)

Key Points |

Abnormal fetal lie or presentation may occur due to fetal size, fetal anomalies, uterine structural abnormalities, multiple gestation, or other factors. Diagnosis is by examination or ultrasonography. Management is with physical maneuvers to reposition the fetus, operative vaginal delivery , or cesarean delivery .

Terms that describe the fetus in relation to the uterus, cervix, and maternal pelvis are

Fetal presentation: Fetal part that overlies the maternal pelvic inlet; vertex (cephalic), face, brow, breech, shoulder, funic (umbilical cord), or compound (more than one part, eg, shoulder and hand)

Fetal position: Relation of the presenting part to an anatomic axis; for vertex presentation, occiput anterior, occiput posterior, occiput transverse

Fetal lie: Relation of the fetus to the long axis of the uterus; longitudinal, oblique, or transverse

Normal fetal lie is longitudinal, normal presentation is vertex, and occiput anterior is the most common position.

Abnormal fetal lie, presentation, or position may occur with

Fetopelvic disproportion (fetus too large for the pelvic inlet)

Fetal congenital anomalies

Uterine structural abnormalities (eg, fibroids, synechiae)

Multiple gestation

Several common types of abnormal lie or presentation are discussed here.

Transverse lie

Fetal position is transverse, with the fetal long axis oblique or perpendicular rather than parallel to the maternal long axis. Transverse lie is often accompanied by shoulder presentation, which requires cesarean delivery.

Breech presentation

There are several types of breech presentation.

Frank breech: The fetal hips are flexed, and the knees extended (pike position).

Complete breech: The fetus seems to be sitting with hips and knees flexed.

Single or double footling presentation: One or both legs are completely extended and present before the buttocks.

Types of breech presentations

Breech presentation makes delivery difficult ,primarily because the presenting part is a poor dilating wedge. Having a poor dilating wedge can lead to incomplete cervical dilation, because the presenting part is narrower than the head that follows. The head, which is the part with the largest diameter, can then be trapped during delivery.

Additionally, the trapped fetal head can compress the umbilical cord if the fetal umbilicus is visible at the introitus, particularly in primiparas whose pelvic tissues have not been dilated by previous deliveries. Umbilical cord compression may cause fetal hypoxemia.

Predisposing factors for breech presentation include

Preterm labor

Uterine abnormalities

Fetal anomalies

If delivery is vaginal, breech presentation may increase risk of

Umbilical cord prolapse

Birth trauma

Perinatal death

Face or brow presentation

In face presentation, the head is hyperextended, and position is designated by the position of the chin (mentum). When the chin is posterior, the head is less likely to rotate and less likely to deliver vaginally, necessitating cesarean delivery.

Brow presentation usually converts spontaneously to vertex or face presentation.

Occiput posterior position

The most common abnormal position is occiput posterior.

The fetal neck is usually somewhat deflexed; thus, a larger diameter of the head must pass through the pelvis.

Progress may arrest in the second phase of labor. Operative vaginal delivery or cesarean delivery is often required.

Position and Presentation of the Fetus

Toward the end of pregnancy, the fetus moves into position for delivery. Normally, the presentation is vertex (head first), and the position is occiput anterior (facing toward the pregnant patient's spine) with the face and body angled to one side and the neck flexed.

Abnormal presentations include face, brow, breech, and shoulder. Occiput posterior position (facing toward the pregnant patient's pubic bone) is less common than occiput anterior position.

If a fetus is in the occiput posterior position, operative vaginal delivery or cesarean delivery is often required.

In breech presentation, the presenting part is a poor dilating wedge, which can cause the head to be trapped during delivery, often compressing the umbilical cord.

For breech presentation, usually do cesarean delivery at 39 weeks or during labor, but external cephalic version is sometimes successful before labor, usually at 37 or 38 weeks.

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Second trimester ultrasound scan

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Citation, DOI, disclosures and article data

At the time the article was created Yuranga Weerakkody had no recorded disclosures.

At the time the article was last revised Khalid Alhusseiny had no financial relationships to ineligible companies to disclose.

Second trimester anatomy scan
2nd trimester anatomy scan
2nd trimester ultrasound scan
Second trimester antenatal ultrasound scan
20 week anatomy scan
Anomaly scan
Second trimester anomaly scan
Fetal anatomical survey

The second trimester scan is a routine ultrasound examination in many countries that is primarily used to assess fetal anatomy and detect the presence of any fetal anomalies.

The second trimester extends from 13 weeks and 0 days to 27 weeks and 6 days of gestation although the majority of these studies are performed between 18 and 23 weeks.

Terminology

Alternate names for the study include second trimester anatomy scan, fetal anomaly scan or TIFFA (targeted imaging for fetal anomalies) .

Radiographic features

The following measurements are routinely obtained to calculate estimated fetal weight (EFW) and estimated date of delivery (EDD):

head circumference (HC)
biparietal diameter (BPD)
abdominal circumference (AC)
femur length (FL)

Second trimester calculation of EDD based on these parameters has a generally accepted error margin of +/- 7 days.

Morphologic assessment

The following structures should be visualized at a routine second trimester morphology ultrasound.

fetal skull: integrity and shape
ventricles and choroid plexus
cavum septum pellucidum
transcerebellar diameter and
cisterna magna
nuchal fold thickness
profile and nasal bone
orbits and lenses
upper lip and palate

Fetal heart and chest

fetal heart rate and rhythm
cardiac situs
four chamber view
left ventricular outflow tract
right ventricular outflow tract
aortic and ductal arches
diaphragm and lungs

Fetal abdomen

stomach (including situs)
kidneys and renal arteries
abdominal wall
umbilical cord insertion
bladder and umbilical arteries
presacral space
fetal gender

Fetal musculoskeletal system

transverse, longitudinal +/- coronal views and skin line
humera, including humeral length (HL)
radius/ulna: both sides
fingers and thumbs, including hand opening
both femora, including femoral length (FL) as part of biometric assessment
both tibia/fibula: sagittal views to demonstrate orientation of the ankles to screen for talipes .

Ancillary findings

cervical length
distance to cervix
liquor volume
umbilical cord including the number of cord vessels and evaluation of knots
1. Document from the Fetal medicine foundation : - www.fetalmedicine.com/fmf/18-23_Weeks_Scan.pdf
2. Document from SOGC Canada : - http://www.sogc.org/guidelines/documents/gui223CPG0903.pdf
3. Document of RCOG : - http://www.rcog.org.uk/womens-health/clinical-guidance/ultrasound-screening
4. Bethune M, Alibrahim E, Davies B, Yong E. A pictorial guide for the second trimester ultrasound. (2013) Australasian journal of ultrasound in medicine. 16 (3): 98-113. doi:10.1002/j.2205-0140.2013.tb00106.x - Pubmed
5. Tan S et.al. Detailed Ultrasound Screening in the Second Trimester: Pictorial Essay of Normal Fetal Anatomy. (2012) Journal of clinical ultrasound : JCU. doi:10.1002/jcu.21918 - Pubmed
6. Tutschek B, Blaas HK, Abramowicz J, Baba K, Deng J, Lee W, Merz E, Platt L, Pretorius D, Timor-Tritsch IE, Gindes L. Three-dimensional ultrasound imaging of the fetal skull and face. (2017) Ultrasound in obstetrics & gynecology : the official journal of the International Society of Ultrasound in Obstetrics and Gynecology. 50 (1): 7-16. doi:10.1002/uog.17436 - Pubmed

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How to Read a Pregnancy Ultrasound Report: Decoding Common Terminology

During pregnancy, you’ll likely have multiple ultrasounds to monitor the growth and health of your baby. Learn how to decipher the terms in your pregnancy ultrasound report.

Fetal ultrasounds are a standard prenatal screening tool and medical imaging test used to monitor your health and the health of your baby during pregnancy.

While pregnancy ultrasounds are a reliable way to track and measure your baby’s progress, reviewing your ultrasound report can be daunting. Pregnancy ultrasound reports often include acronyms and medical terminology that the average person may not recognize and knowing how to read ultrasound numbers and measurements can be intimidating.

If you’re experiencing anxiety waiting to review your ultrasound imaging test results with your OBGYN, family doctor or midwife, this article can help you decode the abbreviated medical language and terms in your report.

By understanding the terms in your ultrasound, you can stress less before your appointment and have confident, informed conversations with your healthcare team.

How does a pregnancy ultrasound work?

During your fetal ultrasound examination, a trained technician called a sonographer will use a hand-held device called a transducer to create and capture sound waves. Too high pitched for human ears to hear, those sound waves travel through your body and bounce off different structures in different ways. The ultrasound machine detects and uses these signals to create an image of the position and shape of your growing pregnancy. These captured images are then interpreted by a radiologist.

There are two main types of ultrasound procedures done during pregnancy:

Transabdominal scan (TAS): A sonographer will squeeze gel onto your belly and then run the transducer over the surface of your skin to capture the fetal anatomy of your growing baby.
Transvaginal scan (TVS): A sonographer will insert a lubricated wand into your vagina to capture more detailed images of your uterus, ovaries and fallopian tubes, allowing for a closer look at your pregnancy and determining any early pregnancy complications.

Early in your pregnancy, you’ll likely have both an abdominal ultrasound and transvaginal ultrasound, since the embryo is so small that the transducer successfully captures more details inside the vaginal canal than it can outside the abdomen. From the second trimester onwards, you’ll likely only have abdominal ultrasounds.

How to read a fetal ultrasound report

What does BPD mean on an ultrasound? What about CRL? Here’s an alphabetical list of the most common medical acronyms you’ll encounter when reviewing your pregnancy ultrasound results, with an explanation of each.

AC (Abdominal circumference):

The measurement of the fetus’s abdomen used to assess fetal growth and development.

AF (Amniotic fluid):

A clear liquid that surrounds the fetus during pregnancy. Contained in the amniotic sac, AF helps cushion the fetus, allowing for safe movement and regulating environmental temperature. AF can be measured using the Amniotic Fluid Index at any time after the 24-week mark of a pregnancy.

BPD (Biparietal diameter):

A standard used to assess fetal growth and development by measuring the distance between two sides of a fetus’ head. What does BPD mean for your ultrasound? BPD can help your practitioner determine gestational age when measured between 14 and 20 weeks of pregnancy.

CPR (Cerebroplacental ratio):

An obstetric tool used to measure fetal growth and adverse pregnancy outcomes by assessing cardiac output. CPR is typically measured within 2 weeks of delivery to determine placental sufficiency before delivery.

CRL (Crown-rump length):

A measurement of the embryo or fetus from the top of its head to the bottom of its torso used to estimate gestational age. CRL is used to assess age between weeks 6 and 13 of pregnancy, after which other measurements like BPD and head circumference (HC) may be more accurate.

EDD (Estimated date of delivery):

A calculation to determine the most likely date of spontaneous natural birth. EDD can be determined by reviewing ovulation and menstruation dates prior to conception or by examining the size of the uterus through a pelvic exam.

EFW (Estimated fetal weight):

EFW is a measurement determined by assessing the size and measurements of various parts of a fetus, including the head circumference (HC), abdominal circumference (AC) and femur length (FL). EFW can be determined at any point after the 10-week mark of a pregnancy.

FGR (Fetal growth restriction):

Is defined as a low fetal weight less than the 10th percentile in weight for gestational age, taking into consideration the growth potential of the fetus. Depending on the fundal height—the distance between the pubic bone and the top of the uterus—FGR may be assessed throughout the pregnancy.

FHM (Fetal heart rate monitoring):

Monitoring fetal heart rate movements allows your healthcare provider to assess the health of the fetus. The fetus’ FHM can be assessed internally using a transvaginal ultrasound in early pregnancy or externally using a Doppler ultrasound during later stages of pregnancy or labor.

FL (Femur length):

A measurement of the length of the fetus’ thighbone used to help estimate fetal growth and assess development. FL is measured during the second and third trimesters of pregnancy.

GA (Gestation age):

This measurement determines the age of the pregnancy and helps assess the health of the mother and fetus. GA can be determined by reviewing the LMP date, fundal height and ultrasound images.

GS (Gestational sac):

The gestational sac is a fluid-filled structure that surrounds and protects the embryo during the first weeks of pregnancy. Measuring the diameter of the GS during an ultrasound can help determine gestational and fetal age and assess the health of the pregnancy. This measurement is called the mean gestational sac diameter (MSD) and may be taken in the first trimester.

HC (Head circumference):

A measurement of the circumference of the fetus’ head used to determine fetal growth and development in combination with BPD, FL and AC measurements. HC is measured during the second and third trimesters of pregnancy.

LGA (Large gestational age):

LGA is a descriptor indicating that a newborn baby weighs more than usual for the length of pregnancy. LGA indicators can be assessed after the 20th week of pregnancy and may be determined by ultrasound or monitoring the mother’s weight gain during pregnancy.

LMP (Last menstrual period):

Date of the mother’s last menstrual period is used to determine the date of delivery and may be requested at the beginning of pregnancy to determine the length of gestation and approximate delivery date.

MSD (Mean gestational sac diameter):

The measurement of the GS using an ultrasound. This measurement determines the gestational age and expected due date of a pregnancy.

NT (Nuchal translucency):

The measurement of the amount of fluid behind the neck of a developing fetus. NT can be assessed by ultrasound between the 11th and 13th week of pregnancy and helps determine the risk of Down Syndrome and other genetic conditions in the developing fetus.

OFD (Occipital-frontal diameter):

Used to assess the growth and development of the fetus, the OFD is the measurement between the back of the head and the forehead of the fetus. This measurement is taken during the second and third trimesters of pregnancy and can be used in combination with BPD to determine the shape of the head.

SGA (Small for gestational age):

SGA is a descriptor indicating that a newborn baby weighs less than usual for the length of pregnancy. SGA indicators can be assessed after the 20th week of pregnancy and may be determined by ultrasound, checking placental blood flow or monitoring the mother’s weight gain during pregnancy.

How PocketHealth can help you access and understand your fetal ultrasound report

You’ll likely be eager to review your prenatal ultrasound images and results. PocketHealth gives you quick access to your pregnancy ultrasound images and reports, as soon as they’re released by the hospital imaging department or imaging clinic—often before your scheduled appointment with your OBGYN, referring family doctor or midwife. You can also securely store your results to any device and share the high-quality images with friends and family during all stages of your pregnancy. Access your records here.

The medical terms, acronyms and assessments found in your ultrasound report won’t be light reading, but Report Reader can help. Report Reader provides definitions for the medical terminology in your report, making it easier for you to understand your results and feel informed and confident at your follow-up appointments.

You can also get personalized insights based on your report. MyCare Navigator spotlights follow-up suggestions and can help you determine the best questions to ask at your next appointment using the Ask My Doctor feature. You’ll always arrive ready to participate in your care at your next prenatal appointment.

Feel confident and in control of your pregnancy

Pregnancy is often an exciting time but can feel nerve-wracking because many of the changes happening to your body are outside of your control. What you do have control over is understanding how your pregnancy progresses, including a better understanding of the medical acronyms and terminology in your ultrasound report.

Gaining knowledge of the medical terms in your report and understanding what your ultrasound images are capturing can ease any anxieties you might have about your baby’s growth, their health and your own wellbeing. More importantly, the knowledge you acquire also allows you to feel more informed and confident throughout your pregnancy when speaking with any member of your healthcare team.

How PocketHealth works

Learn more about how you can use PocketHealth to access and share your pregnancy ultrasound images and results.

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Routine ultrasound for fetal assessment before 24 weeks' gestation

Ultrasound examination of pregnancy before 24 weeks gestation may lead to more accurate dating and earlier diagnosis of pathology, but may also give false reassurance. It can be used to monitor development or diagnose conditions of an unborn baby. This review compares the effect of routine or universal, ultrasound examination, performed before 24 completed weeks' gestation, with selective or no ultrasound examination.

To assess the effect of routine pregnancy ultrasound before 24 weeks as part of a screening programme, compared to selective ultrasound or no ultrasound, on the early diagnosis of abnormal pregnancy location, termination for fetal congenital abnormality, multiple pregnancy, maternal outcomes and later fetal compromise.

To assess the effect of first trimester (before 14 weeks) and second trimester (14 to 24 weeks) ultrasound, separately.

Search methods

We searched Cochrane Pregnancy and Childbirth’s Trials Register, ClinicalTrials.gov, and the World Health Organization's International Clinical Trials Registry Platform (ICTRP) on 11 August 2020. We also examined the reference lists of retrieved studies.

Selection criteria

We included randomised controlled trials (RCTs), quasi‐RCTs, cluster‐RCTs and RCTs published in abstract form. We included all trials with pregnant women who had routine or revealed ultrasound versus selective ultrasound, no ultrasound, or concealed ultrasound, before 24 weeks' gestation. All eligible studies were screened for scientific integrity and trustworthiness.

Data collection and analysis

Two review authors independently assessed trials for eligibility and risk of bias, extracted data and checked extracted data for accuracy. Two review authors independently used the GRADE approach to assess the certainty of evidence for each outcome

Main results

Our review included data from 13 RCTs including 85,265 women. The review included four comparisons. Four trials were assessed to be at low risk of bias for both sequence generation and allocation concealment and two as high risk. The nature of the intervention made it impossible to blind women and staff providing care to treatment allocation. Sample attrition was low in the majority of trials and outcome data were available for most women. Many trials were conducted before it was customary for trials to be registered and protocols published.

First trimester routine versus selective ultrasound: four studies, 1791 women, from Australia, Canada, the United Kingdom (UK) and the United States (US).

First trimester scans probably reduce short‐term maternal anxiety about pregnancy (risk ratio (RR) 0.80, 95% confidence interval (CI) 0.65 to 0.99; moderate‐certainty evidence). We do not have information on whether the reduction was sustained.

The evidence is very uncertain about the effect of first trimester scans on perinatal loss (RR 0.97, 95% CI 0.55 to 1.73; 648 participants; one study; low‐certainty evidence) or induction of labour for post‐maturity (RR 0.83, 95% CI 0.50 to 1.37; 1474 participants; three studies; low‐certainty evidence).

The effect of routine first trimester ultrasound on birth before 34 weeks or termination of pregnancy for fetal abnormality was not reported.

Second trimester routine versus selective ultrasound: seven studies, 36,053 women, from Finland, Norway, South Africa, Sweden and the US.

Second trimester scans probably make little difference to perinatal loss (RR 0.98, 95% CI 0.81 to 1.20; 17,918 participants, three studies; moderate‐certainty evidence) or intrauterine fetal death (RR 0.97, 95% CI 0.66 to 1.42; 29,584 participants, three studies; low‐certainty evidence).

Second trimester scans may reduce induction of labour for post‐maturity (RR 0.48, 95% CI 0.31 to 0.73; 24,174 participants, six studies; low‐certainty evidence), presumably by more accurate dating.

Routine second trimester ultrasound may improve detection of multiple pregnancy (RR 0.05, 95% CI 0.02 to 0.16; 274 participants, five studies; low‐certainty evidence).

Routine second trimester ultrasound may increase detection of major fetal abnormality before 24 weeks (RR 3.45, 95% CI 1.67 to 7.12; 387 participants, two studies; low‐certainty evidence) and probably increases the number of women terminating pregnancy for major anomaly (RR 2.36, 95% CI 1.13 to 4.93; 26,893 participants, four studies; moderate‐certainty evidence).

Long‐term follow‐up of children exposed to scans before birth did not indicate harm to children's physical or intellectual development (RR 0.77, 95% CI 0.44 to 1.34; 603 participants, one study; low‐certainty evidence).

The effect of routine second trimester ultrasound on birth before 34 weeks or maternal anxiety was not reported.

Standard care plus two ultrasounds and referral for complications versus standard care: one cluster‐RCT, 47,431 women, from Democratic Republic of Congo, Guatemala, Kenya, Pakistan and Zambia.

This trial included a co‐intervention, training of healthcare workers and referral for complications and was, therefore, assessed separately.

Standard pregnancy care plus two scans, and training and referral for complications, versus standard care probably makes little difference to whether women with complications give birth in a risk appropriate setting with facilities for caesarean section (RR 1.03, 95% CI 0.89 to 1.19; 11,680 participants; moderate‐certainty evidence). The intervention also probably makes little to no difference to low birthweight (< 2500 g) (RR 1.01, 95% CI 0.90 to 1.13; 47,312 participants; moderate‐certainty evidence). The evidence is very uncertain about whether the community intervention (including ultrasound) makes any difference to maternal mortality (RR 0.92, 95% CI 0.55 to 1.55; 46,768 participants; low‐certainty evidence).

Revealed ultrasound results (communicated to both patient and doctor) versus concealed ultrasound results (blinded to both patient and doctor at any time before 24 weeks): one study, 1095 women, from the UK.

The evidence was very uncertain for all results relating to revealed versus concealed ultrasound scan (very low‐certainty evidence).

Authors' conclusions

Early scans probably reduce short term maternal anxiety.

Later scans may reduce labour induction for post‐maturity. They may improve detection of major fetal abnormalities and increase the number of women who choose termination of pregnancy for this reason. They may also reduce the number of undetected twin pregnancies. All these findings accord with observational data.

Neither type of scan appears to alter other important maternal or fetal outcomes, but our review may underestimate the effect in modern practice because trials were mostly from relatively early in the development of the technology, and many control participants also had scans. The trials were also underpowered to show an effect on other important maternal or fetal outcomes.

Plain language summary

Routine ultrasound scans for babies before 24 weeks of pregnancy.

We set out to determine the effect of routine ultrasound scans early in pregnancy (before 24 weeks). This was in comparison to no scan at all, or scans only when a clinical problem was suspected, such as if the woman has vaginal bleeding, or the baby is at high risk of having an abnormality.

What is the issue?

Ultrasound scans send out high‐frequency sound waves directed to the area being examined, and use the reflected sound to make an image. This review considers two types of scan in the first half of pregnancy. Early scans (before 14 weeks) mainly aim to count the number of babies, to check they are growing in the correct place and check the pregnancy dates. Later scans, typically done around 18 to 24 weeks, recheck all the above, and also examine the baby's anatomy and whether the placenta (afterbirth) is in the correct place. Both types of scan may cause parental anxiety and a false positive diagnoses could lead to harm. The aim of this review is to compare routine with selective or no scans.

Why is this important?

It has been assumed that routine scans before 24 weeks' gestation will result in the earlier detection of problems and improve management and the pregnancy outcome. The alternative is selective scans for specific reasons.

What evidence did we find?

We searched for randomised controlled trials. We found 13 studies including 85,265 women. We included two main comparisons.

Routine early scanning

Ultrasound scans in the first 14 weeks reduced short‐term maternal worries about the pregnancy. There was no evidence of a clear effect on induction of labour to prevent the pregnancy going overdue, loss of the baby, early birth (before 34 weeks) or mothers choosing termination for baby abnormalities.

Routine later scanning

Second trimester scans, at 14 to 24 weeks, increased detection of baby abnormalities, and more women chose termination of pregnancy for this reason. There was no evidence of an effect on perinatal loss. Induction of labour to prevent the pregnancy going overdue was reduced. No studies reported how it affected maternal anxiety. Multiple pregnancies were more likely to be detected by 24 weeks. Long‐term follow‐up of children exposed to these scans did not indicate that they were harmful to children's physical or intellectual development.

We also found one trial from a group of low and middle income countries, comparing a combination of two scans and specialist training of health professionals and referral of women with complications, with selective scans and routine care. The intervention did not alter the number of women delivering in a hospital with caesarean section facility. Nor did it appear to reduce maternal deaths or the numbers of low‐birthweight babies, although the evidence was very uncertain.

We also found one trial where all women underwent scans but the results were revealed to the health care professionals in half the cases. This trial showed no important effect of revealing the scan results but the evidence was very uncertain.

Most studies were carried out relatively early in the development of scan technology and when training in its use was less advanced. In most trials a large proportion of women in the control groups received a scan too.

What does this mean?

Early scans probably reduce maternal worries about the baby in the short term. Later scans may reduce labour induction to prevent the pregnancy going overdue. They may also improve detection of major abnormalities in the baby and increase the number of women who choose pregnancy termination for this reason. They may also reduce the number of undetected twin pregnancies. All these findings accord with common sense.

Although neither type of scan appears to alter other important outcomes, our review may underestimate the effect in modern practice because the trials were mostly from relatively early in the development of scan technology, and many participants in the control arms also had scans.

Summary of findings

Summary of findings 1.


Fetal ultrasound assessment before 24 weeks' gestation 4 studies, 1791 women, four countries (Canada, United Kingdom, USA and Australia) First trimester routine ultrasound First trimester selective ultrasound
	(95% CI)

	Study population		RR 0.80 (0.65 to 0.99)	634 (1 RCT)	⊕⊕⊕⊝ MODERATE
	395 per 1000	316 per 1000 (257 to 391)
	Study population		RR 0.97 (0.55 to 1.73)	648 (1 RCT)	⊕⊕⊝⊝ LOW	Defined as miscarriage, termination of pregnancy, intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital
	67 per 1000	65 per 1000 (37 to 116)
	Study population		RR 0.83 (0.50 to 1.37)	1474 (3 RCTs)	⊕⊕⊝⊝ LOW
	82 per 1000	68 per 1000 (41 to 112)
	Study population		‐	(0 studies)	‐	This outcome was not reported.
	see comment	see comment
	Study population		‐	(0 studies)	‐	This outcome was not reported.
	see comment	see comment
* (and its 95% confidence interval) is based on the assumed risk in the comparison group and the of the intervention (and its 95% CI). Confidence interval; randomised controlled trial; Risk ratio.
We are very confident that the true effect lies close to that of the estimate of the effect We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Studies with design limitations, including poor reporting of allocation concealment methods (‐1).

2 Wide 95% CI crossing the line of no effect and number of events is below the requirement of optimal information size (‐1).

3 Short‐term maternal anxiety; no information on long‐term maternal anxiety.

Summary of findings 2


Fetal ultrasound assessment before 24 weeks' gestation 7 studies, 36,053 women, five countries (South Africa, USA, Norway, Finland, Sweden) Second trimester routine ultrasound Second trimester selective ultrasound
	(95% CI)

	Study population		RR 0.98 (0.81 to 1.20)	17918 (3 RCTs)	⊕⊕⊕⊝ MODERATE	Defined as miscarriage, termination of pregnancy, intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital
	22 per 1000	21 per 1000 (18 to 26)
	Study population		RR 0.48 (0.31 to 0.73)	24174 (6 RCTs)	⊕⊕⊕⊝ MODERATE
	28 per 1000	14 per 1000 (9 to 21)
	Study population		RR 2.36 (1.13 to 4.93)	26893 (4 RCTs)	⊕⊕⊕⊝ MODERATE
	1 per 1000	2 per 1000 (1 to 3)
	Study population		‐	(0 studies)	‐	This outcome was not reported.
	see comment	see comment
	Study population		‐	(0 studies)	‐	This outcome was not reported.
	see comment	see comment
* (and its 95% confidence interval) is based on the assumed risk in the comparison group and the of the intervention (and its 95% CI). Confidence interval; randomised controlled trial; Risk ratio.
We are very confident that the true effect lies close to that of the estimate of the effect We are moderately confident in the effect estimate: The true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different Our confidence in the effect estimate is limited: The true effect may be substantially different from the estimate of the effect We have very little confidence in the effect estimate: The true effect is likely to be substantially different from the estimate of effect

1 Contributing studies had design limitations (‐1).

2 Studies had high statistical heterogeneity (I 2 = 71%) and design limitations (‐1) (‐0.25 for statistical heterogeneity and ‐0.75 for design limitations to avoid double penalty).

Diagnostic ultrasound examination may be employed at various time points in pregnancy, often in the first or second trimester of pregnancy. It may be done routinely as a screening test or selectively to investigate a suspected clinical problem. The assumption underlying routine ultrasound in all pregnancies is that it will enable earlier detection of potential problems and improve management of pregnancy complications. Conversely, the risks are that false positive results will do harm. The focus of this review is to measure the effect of routine ultrasound examination performed before 24 completed weeks' gestation to that of selective or no ultrasound examination.

Description of the condition

Early pregnancy ultrasound examination might result in the earlier detection of abnormal pregnancy location, pregnancy viability, fetal structural abnormalities, molar pregnancy, multiple pregnancy and more accurate dating ( Chen 2019 ; García Fernández 2019 ; Peek 1994 ). Early detection of ectopic pregnancy may allow earlier and safer treatment. Early detection of fetal abnormality might offer opportunities for pregnancy termination, or occasionally other treatment. More accurate dating and early detection of multiple pregnancy, or abnormally invasive placentas, may also allow improved management later in the pregnancy ( Peek 1994 ). However, the examination may cause parental anxiety and false positive diagnoses may lead to iatrogenic harm ( Barnett 2002 ; Salvesen 1995 ).

Description of the intervention

We included studies that compared routine ultrasound as a screening tool to selective ultrasound or no ultrasound. We included any ultrasound scan intended to be done before 24 weeks' gestation. Selective ultrasound is any clinician‐initiated ultrasound that is not part of the patient's routine care. Selective ultrasound examination may have been employed in a variety of specific circumstances during pregnancy; for example, if a woman presented with bleeding in early pregnancy or where the fetus was perceived to be at particularly high risk of malformation. We assessed both ultrasound in the first trimester (before 14 weeks) and in the second trimester (before 24 weeks).

The focus of this review is routine ultrasound before 24 weeks' gestation; late pregnancy screening after 24 weeks' gestation has been addressed in another Cochrane Review ( Bricker 2015 ).

How the intervention might work

Ultrasound screening before 24 weeks' gestation could lead to earlier detection of pregnancy‐related problems and thus allow improved management of these conditions ( Glanc 2018 ; Peek 1994 ).

Many pregnant women appreciate seeing their baby on ultrasound. However, the diagnosis of potential fetal abnormalities may cause anxiety. It is therefore important to consider women's satisfaction in having an ultrasound examination performed ( Hofmeyr 2009 ).

Routine ultrasound before 24 weeks, especially in the first trimester, may improve the accuracy of pregnancy dating and thereby affect the number of pregnancies undergoing induction for post‐maturity ( Middleton 2018 ).

Routine ultrasound before 24 weeks' gestation may improve detection of placental problems, placenta praevia, placenta accreta and vasa praevia. Early detection of these high‐risk pregnancies may improve clinical management ( Panaiotova 2019 ).

Early detection of multiple pregnancy may help pregnancy and birth planning in many ways. Early determination of chorionicity and amnionicity helps to detect pregnancies at highest risk for complications, allowing for early expert referral ( Lee 2006 ).

For most fetal abnormalities, the gain from early and correct detection will be mediated by allowing women choices on pregnancy termination, and there are a few abnormalities where in utero treatment may be offered ( Chen 2019 ; García Fernández 2019 ).

Why it is important to do this review

The use of routine pregnancy ultrasound needs to be considered in the context of potential hazards and limited resources. Implementing routine ultrasound should be based on evidence of benefit. Will the information that clinicians can obtain from routine ultrasound alter their management and thus improve the pregnancy outcome? In addition, the psychological effect of ultrasound examinations on pregnant women is important to consider. This may be either negative (for instance, anxiety following false‐positive identification of fetal abnormality) or positive (for example, reduced anxiety).

Criteria for considering studies for this review

Types of studies.

Randomised controlled trials (RCTs), quasi‐RCTs, cluster‐RCTs. RCTs published only in abstract form were eligible if sufficient information was available to assess eligibility and risk of bias. Cross‐over studies were excluded.

Types of participants

Pregnant women, before 24 weeks' gestation.

Types of interventions

Eligible interventions were routine or revealed ultrasound screening versus selective ultrasound, or concealed ultrasound or no ultrasound for both the 'first trimester' and 'second trimester' of pregnancy. Revealed ultrasound means that results are communicated to both patient and doctor and concealed ultrasound means that the results are blinded to both patient and doctor. We included studies with ultrasound examinations at any time before 24 weeks.

We defined 'first trimester' as earlier than 14 weeks. We defined 'second trimester' as 14 weeks or later.

Types of outcome measures

Primary outcomes.

Maternal anxiety
Perinatal loss (defined as miscarriage, termination of pregnancy or intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital). As requested by the World Health Organization (WHO), we have added the following non‐prespecified similar outcomes: Perinatal death (fetal death after 24 completed weeks gestation and before six completed days of life), perinatal death, excluding those because of lethal malformations, miscarriage (fetal loss before 20 weeks).

Secondary outcomes

Diagnoses of the following conditions.

Intrauterine fetal death (IUFD) (all fetal losses at or after 20 weeks' gestation)
Mean gestational age at birth
Early detection of multiple pregnancy before 24 weeks' gestation
Detection of multiple pregnancy before labour (non‐prespecified)
Early detection of chorionicity
Ectopic pregnancy prior to clinical presentation (suspected and confirmed by surgical and/or medical treatment and/or histopathology)

Maternal outcomes

Women’s views of care/satisfaction
Birth in a risk‐appropriate setting
Number of fetal ultrasound scans
Number of antenatal visits
Antenatal hospital admission (non‐prespecified)
Antenatal care utilisation (four or more visits) (non‐prespecified)
Caesarean section rate
Induction of labour for post‐maturity

Induction of labour for any cause (non‐prespecified)

Termination of pregnancy for any cause
Detection of fetal abnormality before 24 weeks' gestation (non‐prespecified)
Termination of pregnancy for major anomaly
Appropriately timed serum screening tests (non‐prespecified)
Appropriately timed anomaly scan (18 to 22 weeks) (non‐prespecified)
Maternal mortality (non‐prespecified)

Complications for infants and children

Serious neonatal morbidity (composite outcome including hypoxic ischaemic encephalopathy, intraventricular haemorrhage, bronchopulmonary dysplasia, necrotising enterocolitis)

Neonatal death (neonatal death during the first 28 days of life) (non‐prespecified outcome)

Admission to neonatal intensive or special care unit (non‐prespecified outcome)
Birth before 34 weeks' gestation
Mean birthweight (g) (non‐prespecified outcome)
Low birthweight (less than 2500 g) (non‐prespecified outcome)
Very low birthweight (less than 1500 g)
Small for gestational age (non prespecified outcome)
Long‐term infant neurodevelopmental outcome (impairment at two years)

Potential challenges of routine ultrasound

Costs of pregnancy care

Search methods for identification of studies

The following methods section of this review is based on a standard template used by Cochrane Pregnancy and Childbirth.

Electronic searches

We searched Cochrane Pregnancy and Childbirth’s Trials Register by contacting their Information Specialist (11 August 2020).

The Trials Register is a database containing over 25,000 reports of controlled trials in the field of pregnancy and childbirth. It represents over 30 years of searching. For full current search methods used to populate Pregnancy and Childbirth’s Trials Register including the detailed search strategies for CENTRAL, MEDLINE, Embase and CINAHL; the list of handsearched journals and conference proceedings, and the list of journals reviewed via the current awareness service, please follow this link.

Briefly, Cochrane Pregnancy and Childbirth’s Trials Register is maintained by their Information Specialist and contains trials identified from:

monthly searches of the Cochrane Central Register of Controlled Trials (CENTRAL);
weekly searches of MEDLINE (Ovid);
weekly searches of Embase (Ovid);
monthly searches of CINAHL (EBSCO);
hand searches of 30 journals and the proceedings of major conferences;
weekly current awareness alerts for a further 44 journals plus monthly BioMed Central email alerts.

Search results are screened by two people and the full text of all relevant trial reports identified through the searching activities described above is reviewed. Based on the intervention described, each trial report is assigned a number that corresponds to a specific Pregnancy and Childbirth review topic (or topics), and is then added to the Register. The Information Specialist searches the Register for each review using this topic number rather than keywords. This results in a more specific search set that will be fully accounted for in the relevant review sections ( Included studies , Excluded studies , Studies awaiting classification or Ongoing studies ).

Using the search methods detailed in Appendix 1 . we also searched ClinicalTrials.gov and the available databases that contribute to the WHO International Clinical Trials Registry Platform (ICTRP) (11 August 2020) for unpublished, planned and ongoing trial reports.

Searching other resources

We also searched the reference lists of retrieved studies.

We did not apply any language or date restrictions

Selection of studies

Two review authors independently assessed for inclusion all the potential studies we identified as a result of the search strategy. We resolved any disagreement through discussion or, if required, we consulted a third senior review author.

We created a study flow diagram to map out the number of records identified, included and excluded: Figure 1 .

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Figure 1 ‐ process for using the Cochrane Pregnancy and Childbirth criteria for assessing the trustworthiness of a study

Screening eligible studies for scientific integrity and trustworthiness

All studies meeting our inclusion criteria were also evaluated by two review authors against predefined criteria to select studies that were deemed to be sufficiently trustworthy to be included in the analysis, based on available information.

Research governance

No prospective trial registration for studies published after 2010 without plausible explanation
When requested, trial authors refuse to provide/share the protocol and/or ethics approval letter
Trial authors refuse to engage in communication with the Cochrane Review authors
Trial authors refuse to provide individual patient data upon request, with no justifiable reason

Baseline characteristics

Characteristics of the study participants being too similar (distribution of the mean and standard deviation (SD) being excessively narrow or excessively wide, as noted by Carlisle 2017 )

Feasibility

Implausible numbers (e.g. 500 women with severe cholestasis of pregnancy recruited in 12 months)
(Close to) zero losses to follow up without plausible explanation
Implausible results (e.g. massive risk reduction for main outcomes with small sample size)
Unexpectedly even numbers of women ‘randomised’ including a mismatch between the numbers and the methods, e.g. if they say no blocking was used but still end up with equal numbers, or they say they used blocks of four but the final numbers differ by six.

Studies assessed as being potentially ‘high risk’ would not be included in the review. Where a study was classified as ‘high risk’ for one or more of the above criteria, we planned to contact the study authors to address any possible lack of information or concerns. If adequate information remained unavailable, the study would remain in ‘Studies awaiting classification’ and the concerns and communications with the author (or lack of communication) described.

Data from abstracts would only be included if, in addition to the trustworthiness assessment, the study authors confirmed in writing that the data to be included in the review had come from the final analysis and would not change. If such information was not available or not provided, we planned that the study would remain in ‘Studies awaiting classification’.

Data extraction and management

We designed a form to extract data. For eligible studies, at least two review authors extracted the data using the agreed form. We resolved discrepancies through discussion, or, if required, through consultation with a third review author. We entered data into Review Manager 5 software ( RevMan 2014 ) and checked these data for accuracy. When information regarding any of the above was unclear, we attempted to contact authors of the original reports to obtain further details.

Assessment of risk of bias in included studies

Two review authors independently assessed risk of bias for each study using the criteria outlined in the Cochrane Handbook for Systematic Reviews of Interventions ( Higgins 2011 ). We resolved any disagreement by discussion or by involving a third review author.

For cluster‐randomised trials, we paid particular attention to the following risk of bias: recruitment bias; baseline imbalance; loss of clusters; incorrect analysis; and comparability with individually randomised trials, as outlined in the Cochrane Handbook section 16.3.2 and 16.4.3 ( Higgins 2011 ). For individually randomised trials, we assessed the following domains or risk of bias.

(1) Random sequence generation (checking for possible selection bias)

We have described for each included study the method used to generate the allocation sequence in sufficient detail to allow an assessment of whether it should produce comparable groups.

We assessed the method as:

low risk of bias (any truly random process, e.g. random number table; computer random number generator);
high risk of bias (any non‐random process, e.g. odd or even date of birth; hospital or clinic record number);
unclear risk of bias.

(2) Allocation concealment (checking for possible selection bias)

We have described for each included study the method used to conceal allocation to interventions prior to assignment and will assess whether intervention allocation could have been foreseen in advance of, or during recruitment, or changed after assignment.

We assessed the methods as:

low risk of bias (e.g. telephone or central randomisation; consecutively numbered sealed opaque envelopes);
high risk of bias (open random allocation; unsealed or non‐opaque envelopes, alternation; date of birth);

(3.1) Blinding of participants and personnel (checking for possible performance bias)

Achieving effective blinding for an intervention such as ultrasound is difficult, however, we have described for each included study any attempt to blind study participants and personnel from knowledge of which intervention a participant received. We considered that studies were at low risk of bias if they were blinded, or if we judged that the lack of blinding would be unlikely to affect results. We assessed blinding separately for different outcomes or classes of outcomes.

low, high or unclear risk of bias for participants;
low, high or unclear risk of bias for personnel.

For use in our GRADE assessment of the certainty of evidence, we have defined the term 'process outcome'. We defined a 'process outcome' as a variable that is part of the care pathway that is being guided (and altered) by the ultrasound result. The intervention in a 'process outcomes' is not only the test (ultrasound) but patient management guided by test result (ultrasound finding); therefore, lack of blinding does not apply as a reason to downgrade. However, all other criteria for the assessment of the certainty of evidence still apply.

The following are the process outcomes, for which lack of blinding does not apply as a reason to downgrade:

birth in a risk‐appropriate setting;
number of fetal ultrasound scans;
number of antenatal visits;
antenatal hospital admission (WHO‐requested outcome);
antenatal care utilisation (four or more visits) (WHO‐requested outcome);
induction of labour for post‐maturity;
termination of pregnancy for major anomaly;
appropriately timed serum screening tests (WHO‐requested outcome);
appropriately timed anomaly scan (18 to 22 weeks) (WHO‐requested outcome).

(3.2) Blinding of outcome assessment (checking for possible detection bias)

We have described for each included study the methods used, if any, to blind outcome assessors from knowledge of which intervention a participant received. We assessed blinding separately for different outcomes or classes of outcomes.

We assessed methods used to blind outcome assessment as:

low, high or unclear risk of bias.

(4) Incomplete outcome data (checking for possible attrition bias due to the amount, nature and handling of incomplete outcome data)

We have described for each included study, and for each outcome or class of outcomes, the completeness of data including attrition and exclusions from the analysis. We have stated whether attrition and exclusions were reported and the numbers included in the analysis at each stage (compared with the total randomised participants), reasons for attrition or exclusion where reported, and whether missing data were balanced across groups or were related to outcomes. Where sufficient information was reported, or supplied by the trial authors, we planned to re‐include missing data in the analyses.

We assessed methods as:

low risk of bias (e.g. no missing outcome data; missing outcome data balanced across groups);
high risk of bias (e.g. numbers or reasons for missing data imbalanced across groups; ‘as treated’ analysis done with substantial departure of intervention received from that assigned at randomisation);

We used a cut‐off point of 10% to specify the level of missing data used to assess that a study was at low risk of bias.

(5) Selective reporting (checking for reporting bias)

We have described for each included study how we investigated the possibility of selective outcome reporting bias and what we found.

low risk of bias (where it is clear that all of the study’s pre‐specified outcomes and all expected outcomes of interest to the review have been reported);
high risk of bias (where not all the study’s pre‐specified outcomes have been reported; one or more reported primary outcomes were not pre‐specified; outcomes of interest are reported incompletely and so cannot be used; study fails to include results of a key outcome that would have been expected to have been reported); or the study was not registered.

(6) Other bias (checking for bias due to problems not covered by (1) to (5) above)

We have described for each included study any important concerns we had about other possible sources of bias.

Concerns about bias could include for example, was there a potential source of bias related to the specific study design? Was the trial stopped early due to some data‐dependent process? Was there extreme baseline imbalance? Has the study been claimed to be fraudulent?

We assessed whether each study was free of other problems that could put it at risk of bias:

low risk of other bias;
high risk of other bias;
unclear whether there is risk of other bias.

(7) Overall risk of bias

We made explicit judgements about whether studies were at high risk of bias, according to the criteria given in the Handbook ( Higgins 2011 ). With reference to (1) to (6) above, we assessed the likely magnitude and direction of the bias and whether we considered it was likely to impact on the findings.

Measures of treatment effect

Where data were available we combined results from studies in meta‐analysis.

Dichotomous data

For dichotomous data, we have presented results as summary risk ratios (RRs) with 95% confidence intervals (CIs).

Continuous data

For continuous data, we used the mean difference (MD) if outcomes were measured in the same way between trials. We planned to use the standardised mean difference (SMD) to combine trials that measured the same outcome, but used different methods. We applied the following assessment to the data before inclusion in a meta‐analysis: for scale‐derived continuous data, SDs and means would have to be available; Otherwise, we did not include such data in meta‐analysis, but instead have presented them in the text.

Unit of analysis issues

Cluster‐randomised trials.

We included a cluster‐randomised trial in the analyses. We had planned to adjust results from such trials using the methods described in the Handbook using an estimate of the intracluster correlation co‐efficient (ICC) derived from the trial (if possible), from a similar trial or from a study of a similar population. However, the trial authors of the included trial presented data that had already been adjusted for cluster design effect, and as recommended we used this adjusted data in our analyses. We considered that the intervention in the cluster trial (including training of healthcare staff and broader community activities) meant that it was not appropriate to combine it with other studies in meta‐analysis.

If, in the future, we identify further cluster trials we plan to synthesise the relevant information. We will consider it reasonable to combine the results from both individual and cluster‐randomised trials if there is little heterogeneity between the study designs, and the interaction between the effect of intervention and the choice of randomisation unit is considered to be unlikely.

We will also acknowledge heterogeneity in the randomisation unit and perform an analysis to investigate the effects of the randomisation unit.

Dealing with missing data

For included studies, we have noted levels of attrition. We had planned to explore the impact of including studies with high levels of missing data in the overall assessment of treatment effect by using sensitivity analysis, however, attrition in the included studies was relatively low.

For all outcomes, we carried out analyses, as far as possible, on an intention‐to‐treat basis, i.e. we attempted to include all participants randomised to each group in the analyses, with all participants analysed in the group to which they were allocated, regardless of whether or not they received the allocated intervention. The denominator for each outcome in each trial is the number randomised minus any participants whose outcomes are known to be missing.

For dichotomous outcome data, when synthesizing undesirable outcomes, such as mortality or adverse events, we assumed the event rate of a given outcome is the same in the missing population as it is in the completer population and planned therefore calculate the rate of an event in the completer population and apply it to the missing population to obtain the assumed number of event for intention‐to‐treat analysis. In the event we did not carry out this planned analyses as the number of deaths and serious adverse events were very similar in the control and intervention groups and overall sample loss was low. We did not apply this missing data assumption to desirable outcomes or to continuous outcome data. If missing data were greater than 10% in a trial, we planned to perform sensitivity analysis.

Assessment of heterogeneity

We assessed statistical heterogeneity in each meta‐analysis using the Tau², I² and Chi² statistics. We regarded heterogeneity as substantial if I² was greater than 30% and either Tau² was greater than zero, or there was a low P value (less than 0.10) in the Chi² test for heterogeneity.

Assessment of reporting biases

If there were 10 or more studies in the meta‐analysis we planned to investigate reporting biases (such as publication bias) using funnel plots. We would assess funnel plot asymmetry visually and if asymmetry was suggested by a visual assessment, we would perform exploratory analyses to investigate it. In this version of the review none of the meta‐analyses included 10 or more trials.

Data synthesis

We carried out statistical analysis using the Review Manager 5 software ( RevMan 2014 ). We used fixed‐effect meta‐analysis for combining data where it was reasonable to assume that studies are estimating the same underlying treatment effect: i.e. where trials are examining the same intervention, and the trials’ populations and methods are judged sufficiently similar. If there was clinical heterogeneity sufficient to expect that the underlying treatment effects would differ between trials, or if substantial statistical heterogeneity was detected, we used a random‐effects meta‐analysis to produce an overall summary provided an average treatment effect across trials was considered clinically meaningful. The random‐effects summary has been treated as the average of the range of possible treatment effects and we have discussed the clinical implications of treatment effects differing between trials. If the average treatment effect was not considered clinically meaningful we planned not to combine trials.

When we used random‐effects analyses, the results have been presented as the average treatment effect with 95% CIs, and the estimates of Tau² and I².

Subgroup analysis and investigation of heterogeneity

We did not plan to carry out subgroup analysis.

Sensitivity analysis

We planned to carry out sensitivity analysis to explore the effect of trial quality assessed by random sequence generation and allocation concealment, high attrition rate (10%), or both, with poor‐quality studies being excluded from the analyses in order to assess whether this makes any difference to the overall result. We did not carry out this planned further analysis as overall attrition rate was very low. Overall attrition was fairly low and we considered that only one study was at high risk of bias for randomisation and this study contributed few data, so we did not consider that further analysis would throw any more light on results.

Summary of findings and assessment of the certainty of the evidence

We assessed the certainty of the evidence using the GRADE approach as outlined in the GRADE handbook in order to assess the certainty of the body of evidence relating to the following outcomes:

Perinatal loss (defined as miscarriage including termination of pregnancy or intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital)

Termination for major abnormality
Induction of labour rate for post‐maturity
Birth before 34 weeks' gestation.

GRADEpro Guideline Development Tool was used to import data from Review Manager 5.3 ( RevMan 2014 ) in order to create ’Summary of findings’ tables. A summary of the intervention effect and a measure of certainty for each of the above outcomes was produced using the GRADE approach. The GRADE approach uses five considerations (study limitations, consistency of effect, imprecision, indirectness and publication bias) to assess the certainty of the body of evidence for each outcome. With RCT data, evidence can be downgraded from 'high certainty' by one level for serious (or by two levels for very serious) limitations, depending on assessments for risk of bias, indirectness of evidence, serious inconsistency, imprecision of effect estimates or potential publication bias.

Summary of findings for the main comparison can be found in Table 1 .

Description of studies

Results of the search.

See study flow diagram ( Figure 2 ).

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Study flow diagram.

The literature search identified 85 relevant papers reporting findings from 32 trials examining ultrasound for fetal assessment before 24 weeks of pregnancy. Trials included 140,417 women. Most studies resulted in several publications or reports. A total of 13 randomised trials (53 reports) were eligible for inclusion in the review.

We have included data from 12 RCTs including 37,842 women, along with one large cluster‐randomised trial that included an additional 47,421 deliveries ( Goldenberg 2018 ).

Three trials (six reports) had no published data ( Belanger 1996 ; Snaith 2004 ; Wald 1988 ). We contacted the authors of these studies and assigned these records to Studies awaiting classification . We added three new trials (six reports) to Ongoing studies after we contacted the authors ( Figueras 2017 ; Pietersma 2018 ; Richter 2020 ). We excluded a further 13 studies (20 reports).

Screening eligible studies for trustworthiness

From the 13 studies included in this review, three did not meet our criteria for trustworthiness, for the following reasons.

We were unsuccessful in our attempt to contact the authors of two studies. Two studies were published only as abstracts and we have not been able to confirm with the trial authors that the data were from the final analyses ( Belanger 1996 , Snaith 2004 ).
For one study, only the trial registration was published, and we were not able to obtain study data from the final analyses from the authors ( Wald 1988 ). Wald 1988 , also did not respond to requests to the authors of the previous Cochrane Review ( Whitworth 2015 ); to date, no results of this study are available.

In all cases, we made every effort to contact the study authors. See Studies awaiting classification .

Included studies

All of the trials included an intervention involving an ultrasound examination before 24 weeks of pregnancy. The dates of the scans, and the number of scans women received, varied in different trials.

Bakketeig 1984 took place in Trondheim, Norway and Eik‐Nes 1984 in Alesund, Norway over the same time period, but were run as separate trials. In Bakketeig 1984 , women in the intervention arm underwent ultrasound examinations in the 19th and 32nd weeks of pregnancy. The control arm received selective ultrasound examinations. In Eik‐Nes 1984 , women in the intervention arm received ultrasound examinations in the 19th and 32nd weeks of pregnancy. The control arm received selective ultrasound examinations. Bakketeig 1984 ran from May 1979 to September 1981. It was funded by the County Public Health office and the authors did not report any conflicts of interests. Eik‐Nes 1984 ran from May 1979 to September 1981 and was funded by the Alesund Central Hospital and Norway's National Institute of Health. Declarations of interest were not reported.

In the Bennett 1982 trial, all women (in both the intervention and control groups) were offered a scan, but while in the intervention group results were revealed in the women's case notes, control group results were concealed, unless they were specifically requested by clinical staff. This occurred in 30% of cases. Information on funding sources or declarations of interest were not reported.

In Bennett 2004 , women received either an early ultrasound (between eight and 12 weeks gestation) or routine care at their first prenatal visit. Women in both the intervention and control group had a routine second trimester ultrasound at 19 weeks. Women were recruited between 31 December 1999 and 11 April 2002. Information on funding sources or declarations of interest were not reported. Similarly, Harrington 2006 randomised women either to early ultrasound examination between eight and 12 weeks of gestation, or routine care, and women in both arms were offered an anomaly ultrasound examination at 20 weeks of gestation. Harrington 2006 took place between February 1999 and October 2001 and was funded by the UK National Health Service (NHS) Executive South East. The authors did not declare any conflicts of interest.

In the Crowther 1999 trial, women were randomised either to routine ultrasound at their first visit or routine care. Both groups completed a questionnaire at the end of the first antenatal visit on their feelings about the pregnancy and their anxiety levels, which were measured on a Likert scale. The Likert scale was used to assess how 'worried', 'relaxed' and 'excited' the women felt about their pregnancies. Responses to these questions could range from 'not at all' to 'very'. Crowther 1999 recruited participants between 1991 and 1995. Information on funding sources or declarations of interest were not reported.

Early ultrasound examination between 10 and 12 weeks’ gestation (but up to 18 weeks) versus routine care with selective scan was the design of the Ewigman 1990 trial, which took place between 1 September 1984 and 31 May 1986. It was funded by a Biomedical Research Support grant from the US Department of Health and Human Services, as well as funds from Advanced Technology Laboratories and the Robert Wood Johnson Family Practice Fellowship Program at the University of Missouri. The authors did not report any conflicts of interest.

In Geerts 1996 , women received either an ultrasound examination between 18 and 24 weeks, or routine antenatal care with selective scans. Women were recruited between November 1991 and August 1992. Information on funding sources or declarations of interest were not reported.

The Goldenberg 2018 trial was a cluster‐randomised trial in low and middle‐income countries. It involved a complex intervention that included training health workers (nurses, midwives and clinical officers) to perform an ultrasound at 16 to 22 and 32 to 36 weeks' gestation in the intervention group. The comparator was routine care. There was such a high level of scanning in the comparison group that the review authors decided the trial would belong to the routine ultrasound versus selective ultrasound comparison. However, as the trial involved a complex intervention, not only scanning the women, but also training health care workers and referring women for complications, we decided to keep Goldenberg 2018 in its own comparison. Goldenberg 2018 took place from July 2014 to May 2016 and was funded by the Bill and Melinda Gates Foundation and the Eunice Kennedy Shriver National Institute of Child Health. Ultrasound equipment was supplied by GE Healthcare. The authors did not declare any conflict of interest.

The RADIUS 1993 trial was a large trial taking place in 92 obstetric practices and 17 family practices across six states in the USA. Women were randomised either to ultrasound examinations between 15 and 22 weeks and 31 and 35 weeks, or selective scan. RADIUS 1993 started on 1 November 1987 and ran until 31 May 1991. It was funded by the National Institute of Child Health and Human Development. The authors did not report conflicts of interest.

In Saari‐Kemppainen 1994 , women were randomised to either ultrasound screening between 16 and 20 weeks or selective ultrasound. Saari‐Kemppainen 1994 recruited between April 1986 and November 1987 and was funded by the Helsinki University Central hospital fund and the Academy of Finland. The authors did not declare any conflict of interest.

In van Dyk 2007 , all participants who presented on a certain day would be randomised in one cluster, either to the intervention group or to the control group. Women received either a second‐trimester routine ultrasound or no ultrasound, but with the possibility for referral for ultrasound scans if there were clinical indications. It included low‐risk pregnancies in a South African community. In the control group, 21.9% of women received an ultrasound scan; therefore, we decided to include the trial in the routine versus selective ultrasound comparison. Women were recruited between June 2002 and May 2004. Information on funding sources or declarations of interest were not reported.

Similarly, in all included studies, women in the intervention group were offered a 'routine' scan, whilst those in the control groups received a scan at the discretion of the clinical staff ('selective scans'). Ultrasound scans in the intervention group may have been the only 'routine' scan offered, or it may have been an additional scan, with women in both intervention and control groups having scans scheduled at a later stage of pregnancy.

Routine ultrasound screening at 15 weeks versus selective scan was the trial design of Waldenstrom 1988 , which took place between October 1985 and March 1987. Funding came from the Bank of Sweden Tercentenery Foundation, Research Council of Dalarna, County Council of Kopparberg, Foundation of Astrid Karlsson, Uppsala University, Foundation of Medical Research and Evaluation in Dalarna. The authors did not report conflicts of interest.

Further details of design, settings, participants, and interventions are set out in the Characteristics of included studies .

Sample sizes

Sample sizes varied in trials, from 218 in a trial in Canada ( Bennett 2004 ) to 15,151 women in a US trial ( RADIUS 1993 ). There was also a large multi‐country cluster trial, with 47,431 births during the study period ( Goldenberg 2018 ).

The earliest trials recruited women in the late 1970s and early 1980s ( Bakketeig 1984 ; Bennett 1982 ; Eik‐Nes 1984 ; Salvesen 1993a). Trials were mainly conducted in high‐resource settings including Australia ( Crowther 1999 ), Canada ( Bennett 2004 ), Finland ( Saari‐Kemppainen 1994 ), Norway ( Bakketeig 1984 ; Eik‐Nes 1984 ), Sweden ( Waldenstrom 1988 ), UK ( Bennett 1982 ; Harrington 2006 ) and USA ( Ewigman 1990 ; RADIUS 1993 ); two trials were carried out in a middle‐income country, namely South Africa ( Geerts 1996 ; van Dyk 2007 ). The large cluster trial recruited women between 2014 and 2016 and was conducted in the Democratic Republic of Congo, Guatemala, Kenya, Pakistan and Zambia ( Goldenberg 2018 ).

Participants

All trials recruited pregnant women. Most women able to give consent were eligible for inclusion. Depending on the time of the intervention women were recruited as early as eight weeks' gestation and up to 24 weeks.

Interventions and comparisons

Eligible comparisons included: first trimester routine scan versus selective or no scan; second trimester routine scan versus no scan; and revealed ultrasound results (communicated to both patient and doctor) versus concealed ultrasound results (blinded to both patient and doctor) at any time before 24 weeks.

As in all trials women in the control group received an ultrasound if clinically indicated, there was no true 'no scan' control group. Furthermore, there was one trial that took place in low‐and‐middle income countries and not only included a routine scan in the intervention group, but also a co‐intervention of training of healthcare workers and a referral for complications, we have added this trial to its own comparison. Therefore, the types of interventions covered in this review are:

First trimester routine scan versus selective scan;
Second trimester routine scan versus selective scan;
Standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications versus standard care with selective scan;
Revealed (ultrasound results communicated to both patient and doctor) versus concealed (ultrasound results blinded to both doctor and patient) scan at any time before 24 weeks.

Apart from the trial of revealed versus concealed results ( Bennett 1982 ), women in trials were randomised to receive a routine scan versus no routine scan. This is not to say that women in comparison groups were denied scans. The control condition was usually "selective" scans or scans as "clinically indicated" (requested by doctors). This meant that in most trials a proportion of women in the control group, and sometimes a large proportion, also received scans. Further, trials frequently focused on evaluating an additional scan; for example, an early dating scan. However, in addition a later fetal anomaly scan would be offered to women in both intervention and control groups. For this reason, our comparisons are between women receiving an intervention scan versus a selective scan, rather than no scan. We have described in the Characteristics of included studies tables the control conditions and (where this was reported) the number of women in control groups receiving selective scans. In three of the trials included in the second trimester comparison, women in the intervention group were also offered trial scans in the third trimester (at approximately 32 weeks) ( Bakketeig 1984 ; Eik‐Nes 1984 ; RADIUS 1993 ).

The aims of scans varied across trials and several of our pre‐specified outcomes were not well‐reported in trials. Our primary outcomes, overall fetal and perinatal loss, were not reported in the same way in all trials; dates and reasons for loss were not always apparent. In our results section we have reported both overall fetal and perinatal loss and where data was available, we have reported data for separate categories of loss (termination of pregnancy, miscarriage, stillbirth and neonatal death). Very little information was available on our second primary outcome: maternal anxiety, and we have no data from these trials on whether scans are associated with any longer‐term impact on maternal psychological well‐being.

We have reported results for several outcomes we had not prespecified in the protocol. Findings from the review will be included in a WHO guideline on antenatal care, and WHO report on several key outcomes including for example low infant birthweight (< 2500 g) and small‐for‐gestational‐age infant. We have therefore reported on these outcomes if data were available; but have indicated that these were not pre‐specified.

Excluded studies

We excluded 13 studies ( Chen 2008 ; Duff 1993 ; Hoglund Carlsson 2016 ; Larsen 1992 ; Leung 2006 ; Nelson 2017 ; Owen 1994 ; Rustico 2005 ; Saltvedt 2006 ; Schifano 2010 ; Schwarzler 1999 ; Votino 2012 ; Zhang 2018 ).

In the Chen 2008 and the Votino 2012 trials, all participants (in both the intervention and control groups) received early ultrasound scans. In the four studies by Hoglund Carlsson 2016 ; Saltvedt 2006 ; Schwarzler 1999 ; and Zhang 2018 , the timing of scans was examined (i.e. earlier versus later scans).

In the Duff 1993 trial, all participants (in both the intervention and control groups) received an early scan and women in the intervention group had an additional scan in the third trimester. In Larsen 1992 , all participants (in both the intervention and control groups) received early scans and both groups received serial ultrasound scans from 28 weeks. Both groups received scans in the third trimester in the Nelson 2017 trial. Owen 1994 looked at women with a high risk of fetal anomaly, with women in the intervention group receiving more frequent scans.

Three trials compared two versus three or four dimensional ultrasound scans ( Leung 2006 ; Rustico 2005 ; Schifano 2010 ).

Risk of bias in included studies

Please find details in Figure 3 and Figure 4 .

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Risk of bias graph: review authors' judgements about each risk of bias item presented as percentages across all included studies.

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Risk of bias summary: review authors' judgements about each risk of bias item for each included study.

Four of the included trials were assessed to be at low risk of bias for both sequence generation and allocation concealment ( Bennett 2004 ; Crowther 1999 ; Goldenberg 2018 ; Harrington 2006 ). Two studies were assessed as being at high risk of bias ( Bennett 1982 ; van Dyk 2007 ) for both sequence generation and allocation concealment. For the rest, studies did not describe methods fully and were therefore assessed as unclear for at least one of the two domains relating to allocation.

The nature of the intervention meant that it was not possible to adequately blind women and staff providing care to treatment allocation. In one study ( Bennett 1982 ) women were randomised to revealed/concealed results; thus, all women had scans, and may not have been aware of the randomisation group. However, even in this study, staff providing care would have been aware of whether or not scan results were in women's maternity case notes. In the remaining studies, women who had scans would have been fully aware of the intervention, and women in control groups aware that they had not had scans. Whether or not women had scans might impact on women's behaviour and on the behaviour of staff providing care (for example, requests for additional tests or interventions). The impact of lack of blinding on outcomes was not simple to assess but all studies were assessed as being at high or unclear risk of bias for blinding.

Incomplete outcome data

Sample attrition was mainly low in these trials and outcome data were available for most women recruited. In two studies there was sample loss, or loss was not balanced across groups ( Bakketeig 1984 ; Ewigman 1990 ); we assessed these to be at high risk of bias. In another study, there was insufficient information on sample attrition or missing data, and this study was assessed to be at unclear risk of bias for this domain ( Goldenberg 2018 ).

Selective reporting

Many of these trials were conducted before it was customary for all trials to be registered and for protocols to be published before studies commenced. Four studies were assessed as high risk of bias for this domain, but this was mainly due to lack of information ( Bennett 1982 ; Bennett 2004 ; RADIUS 1993 ; Saari‐Kemppainen 1994 ).

Other potential sources of bias

We assessed that five trials were at high risk of bias for other sources of bias. The Harrington 2006 trial was stopped early. In other trials ( Bennett 1982 ; Ewigman 1990 ; RADIUS 1993 ; Saari‐Kemppainen 1994 ) there were other factors that meant results were more difficult to interpret. Protocol deviation was a particular issue in these studies, with large proportions of women in the control groups undergoing scans and, or women in the intervention group not attending for trial interventions.

In the Goldenberg 2018 trial, the authors made adjustments for design effect; the adjusted numbers were used whenever possible for the purposes of the review. There was some protocol deviation. In the intervention clusters, 77.6% of women received at least one study ultrasound. There was considerable variation in different settings with regard to ultrasound use in control groups (95% in Pakistan versus less than 5% in African countries).

Other considerations: clusters were stratified by country and took account of baseline differences among settings. However, there was huge variation among cluster sites in terms of baseline mortality rates and maternity care provision and utilisation. Stillbirth rates ranged between 22 to 54 per 1000 and neonatal mortality between 16 to 45 per 1000 infants. Baseline caesarean section rates ranged from 0.1% in Democratic Republic of Congo to 11.4% in Guatemala. Birth location and birth attendant also varied considerably. Despite adjustment to take account of cluster design, these large variations among sites means that overall results are more difficult to interpret.

In the van Dyk 2007 trial, all participants who presented on a certain day would be randomised to either the intervention group or the control group. On some days, women were randomised to ultrasound scanning, and some days to routine care. In the control routine care group, 21.9% of women received an ultrasound scan for clinical reasons; therefore, we decided to include the trial in the routine versus selective ultrasound comparison. There was no adjustment for any possible variation on different days. The analysis of the results was at the level of individual women.

Effects of interventions

See: Table 1 ; Table 2

Comparison 1: First trimester routine ultrasound versus selective ultrasound

Four studies contributed to this comparison ( Bennett 2004 ; Crowther 1999 ; Ewigman 1990 ; Harrington 2006 ).

This outcome was reported in one trial ( Crowther 1999 ), which included 648 women with 634 women completing an anxiety questionnaire at the end of their first antenatal visit. The evidence suggests that women undergoing routine first trimester scans are probably less worried about their pregnancy after the scan (RR 0.80, 95% CI 0.65 to 0.99; 634 participants, one study; moderate‐certainty evidence , downgraded due to study design limitations). However, women had no long‐term follow‐up, and it is not clear whether this effect was sustained throughout pregnancy ( Analysis 1.1 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 1: Maternal anxiety (mother worried about pregnancy)

One trial ( Crowther 1999 ) reported perinatal loss. The evidence is very uncertain about the effect of first trimester scans on pregnancy loss between screened and unscreened groups, giving a difference of 0.65% versus 0.67%, respectively, because the 95% CI is compatible with a wide range of effects that encompass both appreciable benefit and also harm (RR 0.97, 95% CI 0.55 to 1.73; 648 participants, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision) ( Analysis 1.2 ). When assessing only perinatal death , the results were very uncertain for women undergoing routine scans compared with controls (perinatal death is defined as fetal death after 24 completed weeks gestation and before six completed days of life). The unweighted difference was 0.07% versus 0.09%, respectively (RR 0.73, 95% CI 0.23 to 2.31; 1472 participants, two studies; very low‐certainty evidence, downgraded due to a low event rate and imprecision) ( Analysis 1.3 ). Even when excluding lethal abnormalities, compared with controls, there was not enough evidence that first trimester routine scans made any difference in perinatal death (RR 0.52, 95% CI 0.10 to 2.82; 824 participants, one study) ( Analysis 1.4 ). For miscarriage before 20 weeks, there may be little to no difference between the groups (RR 0.84, 95% CI 0.57 to 1.24; 1111 participants, two studies; low‐certainty evidence, downgraded for imprecision due to a low event rate and wide 95% CI crossing the line of no effect) ( Analysis 1.5 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 2: Perinatal loss

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 3: Perinatal death

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 4: Perinatal death (excluding lethal malformations)

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 5: Miscarriage (fetal loss before 20 weeks)

Intrauterine fetal death (all fetal losses at or after 20 weeks' gestation)

One study ( Harrington 2006 ) with 463 women reported one IUFD in the routine scan group as compared to none in the selective scan group. The evidence is very uncertain about the effect of first trimester routine scan on the occurrence of IUFD (RR 2.96, 95% CI 0.12 to 72.32; 463 participants, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision. Imprecision was due to a low event rate and wide 95% CI crossing the line of no effect) ( Analysis 1.6 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 6: IUFD

There was only one study comparing first trimester routine scan to selective scan regarding detecting multiple pregnancy before 24 to 26 weeks’ gestation. Both sets of twins were detected in the screening group, whereas only five out of seven sets of twins (71%) were detected in the selective scan group (RR 0.53, 95% CI 0.03 to 8.19; nine multiple pregnancies, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision. Imprecision was due to a low event rate and sample size and wide 95% CI crossing the line of no effect) ( Analysis 1.7 ). The same study also assessed diagnosis of twins after the onset of labour. Both sets of twins were diagnosed before labour in the screening group, and six out of seven sets of twins (85%) were identified before labour in the control group (RR 0.89, 95% CI 0.05 to 16.36; nine multiple pregnancies, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision. Imprecision was due to a low event rate, small sample size and wide 95% CI crossing the line of no effect ) ( Analysis 1.8 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 7: Detection of multiple pregnancy by 24 to 26 weeks' gestation (number NOT detected)

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 8: Detection of multiple pregnancy before labour (number NOT detected)

Ectopic pregnancy prior to clinical presentation

One study reported detection of ectopic pregnancy prior to clinical presentation (suspected and confirmed by either surgical and/or medical treatment and/or histopathology). There was insufficient evidence to determine whether first trimester scans make any difference in diagnosing ectopic pregnancy before clinical presentation. There was a single ectopic pregnancy in the screened group that was detected before clinical presentation and no ectopic pregnancies in the control group (RR 2.74, 95% CI 0.11 to 66.51; 218 participants, one study; very low‐certainty evidence, downgraded due to study design limitations and imprecision. Imprecision was due to a low event rate, small sample size and wide 95% CI crossing the line of no effect) ( Analysis 1.9 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 9: Ectopic pregnancy before clinical presentation

The evidence is very uncertain about the effect of a routine first trimester ultrasound on the number of women undergoing birth by caesarean section due to wide CIs (RR 1.27, 95% CI 0.99 to 1.61; 1253 participants, three studies; low‐certainty evidence, downgraded due to study design limitations and imprecision) (Analysis 1.10).

Induction of labour for post‐maturity/Induction of labour for any cause (non‐prespecified)

The evidence is very uncertain about the effect of a routine first trimester scan on the number of inductions of labour for post‐maturity pregnancy (RR 0.83, 95% CI 0.50 to 1.37; 1474 participants, three studies; low‐certainty evidence, downgraded due to study design limitations and imprecision) ( Analysis 1.11 ), or inductions of labour for any reason (RR 0.73, 95% CI 0.49 to 1.09; 463 participants, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision) ( Analysis 1.12 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 11: Induction of labour for post maturity

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 12: Induction of labour for any cause

The evidence is very uncertain on whether a first trimester scan makes any difference to the number of women undergoing termination for any cause (RR 0.99, 95% CI 0.14 to 6.95; 463 participants, one study; very low‐certainty evidence, downgraded due to study design limitations and very serious imprecision) ( Analysis 1.13 ). There are no data to assess whether first trimester ultrasound made a difference in a woman's choice to terminate for major abnormality.

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 13: Termination of pregnancy for any cause

One study reported on first trimester screening and appropriately timed serum screening. The evidence is very uncertain about the effect of a first trimester routine scan on the number of women requiring repeat serum screening (RR 0.89, 95% CI 0.45 to 1.76; 602 participants, one study) ( Analysis 1.14 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 14: Appropriately timed serum screening tests (number having repeat screening)

A first trimester routine scan may make little to no difference to the number of women not having an appropriately timed detailed ultrasound examination (RR 0.77, 95% CI 0.55 to 1.08; 602 participants, one study) ( Analysis 1.15 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 15: Appropriately timed anomaly scan (18 to 22 weeks)(number NOT appropriately timed)

Serious neonatal morbidity

One study reported that a first trimester scan may make little to no difference to serious neonatal morbidity (composite outcome including hypoxic ischaemic encephalopathy, intraventricular haemorrhage, bronchopulmonary dysplasia, necrotising enterocolitis) ( Ewigman 1990 ) (RR 0.84, 95% CI 0.50 to 1.39; 824 participants, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision) ( Analysis 1.16 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 16: Serious neonatal morbidity (admission to neonatal intensive care unit)

Low birthweight (non‐prespecified)

The evidence is very uncertain about the effect of first trimester scan on low infant birthweight (less than 2500 g) (RR 2.01, 95% CI 0.99 to 4.08; 594 participants, one study; low‐certainty evidence, downgraded due to study design limitations and imprecision) ( Analysis 1.17 ).

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 17: Low birthweight (less than 2500 g)

The following outcomes were not reported in the studies in this comparison.

Birth before 34 weeks' gestationMean birthweight (g) (non‐prespecified outcome)

Comparison 2: Second trimester routine ultrasound versus selective ultrasound

Eight studies contributed to this comparison ( Bakketeig 1984 ; Eik‐Nes 1984 ; Geerts 1996 ; RADIUS 1993 ; Saari‐Kemppainen 1994 ; van Dyk 2007 ; Waldenstrom 1988 ; Goldenberg 2018 ). However one trial, Goldenberg 2018 , involved a co‐intervention of training sonographers and referral for complications and was the only trial in low‐and middle‐income countries; therefore, this trial was analysed separately in Comparison 3.

This outcome was not reported in any of the trials.

Second trimester scans probably makes little or no difference to pregnancy loss (RR 0.98, 95% CI 0.81 to 1.20; 17,918 participants, three studies; moderate‐certainty evidence, downgraded due to study design limitations) ( Analysis 2.1 ). When assessing perinatal death, ultrasound may make little to no difference (RR 0.88, 95% CI 0.69 to 1.12; 33,911 participants, seven studies; low‐certainty evidence, downgraded due to wide 95% CI crossing the line of no effect) ( Analysis 2.2 ). Even when excluding lethal abnormalities, a second trimester routine scan may make little to no difference in perinatal death (RR 0.68, 95% CI 0.42 to 1.11; 11,316 participants, three studies; low‐certainty evidence, downgraded due to wide 95% CI crossing the line of no effect) ( Analysis 2.3 ). For miscarriage before 20 weeks, routine ultrasound probably makes little to no difference between the groups (RR 0.92, 95% CI 0.78 to 1.08; 9310 participants, one study; low‐certainty evidence, downgraded due to study design limitations) ( Analysis 2.4 ). Routine versus selective ultrasound may make little or no difference to neonatal death (RR 0.79, 95% CI 0.48 to 1.28; 25,396 participants, three studies; low‐certainty evidence, downgraded due to study design limitations) ( Analysis 2.18 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 1: Perinatal loss

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 2: Perinatal death (all babies)

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 3: Perinatal death (excluding lethal malformations)

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 4: Miscarriage (fetal loss before 20 weeks)

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 18: Neonatal death

Four studies reported on IUFD and show little to no difference in the routine scan group versus selective scan (RR 0.97, 95% CI 0.66 to 1.42; 29,584 participants, three studies; low‐certainty evidence, downgraded due to study design limitations and imprecision. Imprecision was due to a low event rate and wide 95% CI crossing the line of no effect) ( Analysis 2.5 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 5: IUFD

Routine second trimester ultrasound may reduce non‐detection of multiple pregnancy before 24 to 26 weeks' gestation (RR 0.05, 95% CI 0.02 to 0.16; 274 participants, five studies; low‐certainty evidence, downgraded due to study limitations) ( Analysis 2.6 ). There is little evidence that routine second trimester ultrasound makes a difference in the detection of multiple pregnancy before labour (RR 0.10, 95% CI 0.01 to 1.74; 135 participants, three studies) ( Analysis 2.7 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 6: Detection of multiple pregnancy by 24 to 26 weeks' gestation (number NOT detected)

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 7: Detection of multiple pregnancy before labour (number NOT detected)

One trial carried out in South Africa presented data on the mean number of ultrasound scans ( Geerts 1996 ). Selective ultrasound resulted in a lower mean number of ultrasound scans as compared to routine ultrasound. In this study, women in the routine ultrasound group had an average of 1.2 scans compared with an average of 0.3 in the selective ultrasound group (MD 0.90, 95% CI 0.84 to 0.96; 990 participants, one study) ( Analysis 2.8 ). The RADIUS 1993 trial reported a mean number of 2.2 ultrasound scans in the routine ultrasound group as opposed to the control group which had a mean of 0.6 (data not shown). In a trial in South Africa, 16.3% of women in the routine ultrasound group had subsequent ultrasound scans in pregnancy, whereas 21.9% had a scan in the selective scan group later in pregnancy ( van Dyk 2007 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 8: Number of fetal ultrasound scans

There was little to no evidence of a difference in number of antenatal hospital admissions between the routine ultrasound group and controls (RR 1.08, 95% CI 0.91 to 1.27; 16,836 participants, five studies) and the mean number of antenatal visits (MD 0.08, 95% CI ‐0.30 to 0.46; 10,306 participants, three studies) was similar in both groups ( Analysis 2.10 ; Analysis 2.9 ). A trial in South Africa reported a mean number of hospital visits, which was 5.8 +/‐ 1.8 in the screening group versus 5.9 +/‐ 2.0 in the selective scan group ( van Dyk 2007 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 9: Number of antenatal visits

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 10: Antenatal hospital admission

The evidence suggests that a second trimester routine ultrasound makes little or no difference to the number of women undergoing caesarean section (RR 1.05, 95% CI 0.98 to 1.12; 22,193 participants, five studies; low‐certainty evidence, downgraded due to study design limitations) ( Analysis 2.11 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 11: Caesarean section rate

Induction of labour for post‐maturity/induction of labour for any cause

Routine ultrasound in the second trimester may reduce induction of labour for suspected post‐maturity (average RR 0.48, 95% CI 0.31 to 0.73; 24,174 participants, six studies; low‐certainty evidence, downgraded for study limitations and heterogeneity. Due to heterogeneity we used random‐effects analysis for this outcome) ( Analysis 2.12 ). Furthermore, induction of labour for any cause may be reduced, however there was high heterogeneity for this outcome and again we used random effects analysis (average RR 0.75, 95% CI 0.56 to 1.00; 23,267 participants, five studies; low‐certainty evidence) ( Analysis 2.13 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 12: Induction of labour for post maturity

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 13: Induction of labour for any cause

Termination of pregnancy for any cause (non‐prespecified)

The evidence is very uncertain about the effect of routine second trimester scan on the number of women terminating pregnancy for any cause (RR 0.99, 95% CI 0.14 to 6.95; 463 participants, one study; low‐certainty evidence, downgraded due to study limitations and imprecision) ( Analysis 2.14 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 14: Termination of pregnancy for any cause

Detection of major fetal abnormality before 24 weeks' gestation (non‐prespecified)

Routine second trimester ultrasound may increase detection of major fetal abnormality before 24 weeks (RR 3.45, 95% CI 1.67 to 7.12; 387 participants, two studies; low‐certainty evidence, downgraded due to design limitations and imprecision. Imprecision due to low event rate and sample size) ( Analysis 2.15 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 15: Detection of fetal abnormality before 24 weeks' gestation

Routine second trimester scan probably increases the number of women terminating pregnancy for major anomaly (RR 2.36, 95% CI 1.13 to 4.93; 26,893 participants, four studies; moderate‐certainty evidence, downgraded due to study limitations) ( Analysis 2.16 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 16: Termination of pregnancy for fetal abnormality

The large RADIUS 1993 study reported on a composite outcome for serious neonatal morbidity and there was very little difference between the ultrasound and control groups (RR 1.03, 95% CI 0.78 to 1.36; 15,281 participants, one study) ( Analysis 2.17 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 17: Serious neonatal morbidity

Routine versus selective ultrasound may make little or no difference to neonatal death (RR 0.79, 95% CI 0.48 to 1.28; 25,396 participants, three studies; low‐certainty evidence, downgraded due to study design limitations) ( Analysis 2.18 ).

Admission to neonatal intensive or special care unit (non‐prespecified)

The evidence suggests little to no difference in admission of infants to intensive or special care unit (definitions may not have been the same in all studies) (RR 0.92, 95% CI 0.84 to 1.01; 17,484 participants, six studies) ( Analysis 2.19 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 19: Admission to neonatal intensive care unit

There is no evidence of a difference in mean birthweight between the two groups (MD 16.79, 95% CI ‐6.44 to 40.03; 23,177 participants, five studies) ( Analysis 2.20 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 20: Mean birthweight (g)

Low birthweight (less than 2500 g)/Very low birthweight (less than 1500 g) (non‐prespecified outcomes)

There was little to no difference between groups for low birthweight (< 2500 g) (average RR 0.92, 95% CI 0.74 to 1.14; 17,728 participants, six studies) or very low infant birthweight (RR 0.75, 95% CI 0.36 to 1.56; 990 participants, one study) ( Analysis 2.21 ; Analysis 2.22 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 21: Low birthweight (less than 2500 g)

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 22: Very low birthweight (< 1500 g)

Small for gestational age (non‐prespecified)

One study reported the number of infants that were small for gestational age and there was no evidence of a difference between groups (RR 1.47, 95% CI 0.92 to 2.35; 964 participants, one study) ( Analysis 2.23 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 23: Small‐for‐gestational age

A follow‐up into childhood of 603 babies included in the Bakketeig 1984 trial suggested that the evidence is uncertain of whether scans during pregnancy have any effect on dyslexia due to imprecision of results (RR 0.77, 95% CI 0.44 to 1.34; 603 participants, one study; low‐certainty evidence) ( Analysis 2.24 ).

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Comparison 2: Second trimester routine versus selective ultrasound, Outcome 24: Dyslexia

Cost of pregnancy care

There were no data to assess the effects of routine ultrasound on the overall cost of care, but RADIUS 1993 estimated the average costs of routine ultrasound to be USD 200/scan, or USD 89.28 per patient.

Ectopic pregnancy prior to clinical presentation (suspected and confirmed by either surgical and/or medical treatment and/or histopathology)

Comparison 3: Standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications versus standard care with selective scan.

The Goldenberg 2018 trial involved a complex intervention including training health workers (nurses, midwives and clinical officers) to perform ultrasound at 18 to 22 and 32 to 36 weeks' gestation compared to no study ultrasound examinations or community intervention. This was a cluster‐randomised trial and for several outcomes trialists adjusted results to take account of both baseline differences in different study areas and of cluster design effect. Data were presented on only a limited number of review outcomes. We used the generic inverse variance method in our data and analysis; although the total sample size is shown in the forest plots the event rates are not. We have therefore included event rates as part of our presentation of results in the text. However, these rates are for illustrative purposes only as they do not reflect the adjustment made by the trialists in calculating relative effects.

This outcome was not reported in the trial.

Perinatal loss (defined as miscarriage including termination of pregnancy or intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital).

Diagnosis of the following condition, intrauterine fetal death.

Adjusted data suggests that standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications probably makes little or no difference to IUFD (RR 0.99, 95% CI 0.94 to 1.04; 46,904 participants; moderate‐certainty evidence, downgraded for study design limitations) (effect estimate based on adjusted data: 675/24,254 versus 628/23,149 in the intervention and control groups respectively) ( Analysis 3.1 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 1: IUFD

The trial also assessed whether or not women with pregnancy complications gave birth in hospital with facilities for caesarean section; again there was little to no differences between groups (RR 1.03, 95% CI 0.89 to 1.19; 11,680 participants, one study; moderate‐certainty evidence, downgraded for study design limitations) (effect estimate based on adjusted data, actual data: 2569/6,152 versus 2252/5,528 in the intervention and control groups respectively (the numerators are the number of complicated labours) ( Analysis 3.2 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 2: Birth in a risk‐appropriate setting

The trialists collected data on the number of women attending for antenatal visits on at least four occasions. Adjusted data suggests there is probably little or no difference between groups (RR 1.03, 95% CI 0.90 to 1.18; 46,904 participants, one study; moderate‐certainty evidence, downgraded for study design limitations) (effect estimate based on adjusted data; actual data: 12,021/24,008 versus 10,866/22,896 in the intervention and control groups respectively) ( Analysis 3.3 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 3: Antenatal care utilisation (4 or more visits)

Evidence suggests that standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications may make little or no difference to caesarean section (RR 0.99, 95% CI 0.94 to 1.04; 46,904 participants, one study; low‐certainty evidence, downgraded for study design limitations and imprecision) (effect estimate based on unadjusted data, actual data: 2919/24,008 versus 2808/22,896 in the intervention and control groups, respectively) ( Analysis 3.4 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 4: Caesarean section rate (unadjusted)

The evidence is very uncertain about whether standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications makes any difference to maternal mortality (RR 0.92, 95% CI 0.55 to 1.55; 46,768 participants, one study; low‐certainty evidence, downgraded for study design limitations and imprecision) (effect estimate based on unadjusted data: 28/23,923 versus 29/22,845 in the intervention and control groups respectively) ( Analysis 3.5 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 5: Maternal mortality (unadjusted)

Neonatal death (non‐prespecified)

The intervention also probably makes little or no difference to neonatal death (RR 0.99, 95% CI 0.86 to 1.14; 45,974 participants, one study; moderate‐certainty evidence, downgraded for study design limitations) (effect estimate based on adjusted data, actual data: 546/23,495 versus 543/22,479 in the intervention and control groups, respectively) ( Analysis 3.6 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 6: Neonatal death

Low birthweight

Moderate‐certainty evidence suggested the intervention probably makes little or no difference to low birthweight (< 2500 g) (RR 1.01, 95% CI 0.90 to 1.13; 47,312 participants, one study; moderate‐certainty evidence, downgraded for study design limitations). (Effect estimate based on adjusted data, actual data: 3223/24,201 versus 3223/23,111 in the intervention and control groups, respectively) ( Analysis 3.7 ).

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Comparison 3: Standard care plus two ultrasounds and referral for complications vs standard care, Outcome 7: Low birthweight (< 2500 g)

The following outcomes were not reported in the study in this comparison:

Potential challenges of systematic ultrasound

Comparison 4: revealed (ultrasound results communicated to both patient and doctor) versus concealed (ultrasound results blinded to both doctor and patient) at any time before 24 weeks..

One study contributed to this comparison with 1,095 women ( Bennett 1982 ).

The evidence is very uncertain about the effect of a revealed ultrasound scan compared to not revealed on pregnancy loss (RR 1.33, 95% CI 0.57 to 3.14; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.1 ) and perinatal death (RR 1.67, 95% CI 0.40 to 6.94; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.2 ). Even when excluding lethal abnormalities the evidence was still found to be of very uncertain for perinatal death (RR 1.33, 95% CI 0.30 to 5.92; 1073 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate).

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Comparison 4: Revealed (ultrasound results communicated to both patient and doctor) versus concealed (ultrasound results blinded to both doctor and patient) at any time before 24 weeks, Outcome 1: Perinatal loss

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Intrauterine fetal death and neonatal death

The evidence is very uncertain about the effect of revealed scans on IUFD (RR 2.00, 95% CI 0.18 to 21.99; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.4 ).

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Detection of multiple pregnancy before 24 to 26 weeks' gestation

The evidence is very uncertain about the effect of revealed scans on detection of multiple pregnancy before 24‐26 weeks (RR 0.17, 95% CI 0.01 to 2.92; 11 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate), respectively ( Analysis 4.5 ).

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The evidence is very uncertain about the effect of revealed scans on women undergoing induction of labour for any reason (RR 0.97, 95% CI 0.76 to 1.24; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.6 ).

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The evidence is very uncertain about the effect of revealed scans on women undergoing termination of pregnancy for any cause (RR 1.17, 95% CI 0.39 to 3.45; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate).( Analysis 4.7 ).

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The evidence is very uncertain about the effect of revealed scans on neonatal deaths (RR 1.50, 95% CI 0.25 to 8.94; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.8 ).

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Low birthweight (< 2500 g)

The evidence is very uncertain about the effect of revealed scans on low birthweight (RR 1.09, 95% CI 0.74 to 1.61; 1062 participants, one study; very low‐certainty evidence, downgraded due to imprecision (wide 95% CI crossing the line of no effect, single study and low event rate) ( Analysis 4.9 ).

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The following outcomes were not reported in the study in this comparison.

Summary of main results

First trimester routine versus selective ultrasound for fetal assessment before 24 weeks' gestation.

There is moderate‐certainty evidence that first trimester scans probably reduces short‐term maternal anxiety about pregnancy, but it is not clear if the effect is sustained (moderate‐certainty evidence).

The evidence is very uncertain about the effect of first trimester scans on pregnancy loss or inductions of labour for post‐maturity (low‐certainty evidence).

The effect of routine first trimester ultrasound on birth before 34 weeks or termination of pregnancy for fetal abnormality was not reported in studies.

Second trimester routine versus selective ultrasound (Maternal outcomes) for fetal assessment before 24 weeks' gestation

Second trimester scans probably makes little to no difference to pregnancy loss or intrauterine fetal death (moderate‐certainty evidence).

Routine ultrasound in the second trimester may reduce induction of labour for suspected post‐maturity (moderate‐certainty evidence).

Routine second trimester ultrasound may increase detection of major fetal abnormality before 24 weeks (moderate‐certainty evidence) and probably increases the number of women terminating pregnancy for major anomaly (moderate‐certainty evidence).

Second trimester routine scans may reduce non‐detection of multiple pregnancy before 24 to 26 weeks' gestation (low‐certainty evidence).

Long‐term follow‐up of children exposed to scans before birth did not indicate that scans are harmful to children's physical or intellectual development (low‐certainty evidence).

The effect of routine second trimester ultrasound on birth before 34 weeks or maternal anxiety was not reported in studies.

Standard care plus two ultrasounds, and co‐intervention of training of healthcare workers and referral for complications versus standard care with selective scan

The additional scans and interventions in the intervention arm probably makes little to no difference to whether or not women with pregnancy complications gave birth in hospital with facilities for caesarean section (moderate‐certainty evidence), low birth weight (< 2500 g) or maternal mortality.

Revealed ultrasound results (communicated to both patient and doctor) versus concealed ultrasound results (blinded to both patient and doctor) at any time before 24 weeks)

Overall completeness and applicability of evidence.

The review includes several large trials, although the eligibility criteria among the trials differ. Therefore, the results may not be generalisable to all women. Additionally, ultrasound itself is unlikely to improve maternal or fetal outcomes; rather, it will be the interventions that could be offered, based on the information provided by ultrasound in particular situations, that alters outcomes.

The majority of studies were carried out in high‐resource settings where the overall level of perinatal mortality is low and the contribution of major fetal abnormality to mortality is higher than in lower‐resource settings. Findings in high‐resource settings may not apply in less‐affluent settings and countries. One trial involving a complex intervention contributed data from low‐ and middle‐income countries.

The different studies were carried out over a time period of more than 30 years. During that time, changes in scanning guidelines, technical advances in equipment, more widespread use of ultrasonography in the world, and training and expertise of operators are likely to have resulted in more effective sonography, particularly for the detection of fetal abnormalities.

For many of the primary outcomes (maternal anxiety and perinatal loss) in this review, the authors recognised a lack of trial evidence.

Quality of the evidence

The review includes several large, well‐designed trials. Lack of blinding is a problem common to all of the studies and this may have an effect on some outcomes. In several studies, a high number of women in the control group also had ultrasound examinations, especially in the Goldenberg 2018 trial, which was a cluster‐RCT conducted in several low‐ and middle‐income countries. In some countries, up to 95% of women in the control group had an ultrasound, whereas in others, only very few women had a scan in the control arm. Key outcomes were adjusted by the trialists and the authors used them whenever available, as per Cochrane guidance.

We used the GRADE approach to assess the certainty of evidence for all primary review outcomes. The certainty of evidence for maternal anxiety and perinatal death was low. Downgrading of evidence was based on including studies with design limitations, imprecision of results and presence of heterogeneity. For some of the outcomes, such as perinatal loss, the event rate was very low. The pooled effect was provided by studies with design limitations, including poor reporting of allocation concealment methods, in all GRADE outcomes. In two of the first trimester outcomes, we downgraded for serious imprecision, due to the wide 95% CI crossing the line of no effect. In one second trimester outcome, we downgraded for inconsistency (serious heterogeneity, I² = 68%).

RCTs published before 1996 were done before the Consolidated Standards of Reporting Trials (CONSORT) statement was first published, and therefore could not be compliant with its standards ( Begg 1996 ).

Potential biases in the review process

The possibility of introducing bias was present at every stage of the reviewing process. We attempted to minimise bias in a number of ways: two review authors assessed eligibility for inclusion, carried out data extraction and assessed risk of bias. Each worked independently. Nevertheless, the process of assessing risk of bias, for example, is not an exact science and includes many personal judgements. Furthermore, the process of reviewing research studies is known to be affected by prior beliefs and attitudes. It is difficult to control for this type of bias in the reviewing process.

While we attempted to be as inclusive as possible in the search strategy, the literature identified was predominantly written in English and published in North American and European journals. Although we did attempt to assess reporting bias, constraints of time meant that this assessment largely relied on information available in the published trial reports and thus, reporting bias was not usually apparent.

Agreements and disagreements with other studies or reviews

Our data showed that routine ultrasound before 14 weeks can reduce maternal anxiety around the time of the scan. Garcia 2002 , a systematic review of studies on women's views about antenatal screening and diagnosis illustrated how attractive ultrasound in pregnancy is to women and their partners. The review included 74 primary studies from 18 countries that employed a wide range of methods ranging from qualitative interviewing to psychometric testing. The main finding was that not all women were aware of the purpose of ultrasound scanning in pregnancy. This lack of knowledge left some women vulnerable to anxiety and disappointment if the scan detected a problem, especially in situations where women were not counselled that the scan was to screen for abnormalities. The lack of information on the intention of scanning before 24 weeks can do also lead to women believing that if no abnormalities are detected, this means that all must be well. The review recommended that parents need clear information about the purpose and limitations of scans. Women need to know what to expect so that they can make informed decisions about their care and so that they are prepared for potential abnormal findings.

With regard to similar outcomes in this review, the RADIUS 1993 of 15,530 women assessed if screening ultrasound in low‐risk pregnancies would improve perinatal outcomes. This trial showed no differences in maternal outcomes and found similar rates of induced abortion and Caesarean section.

Implications for practice

This evidence suggests that first trimester ultrasound may reduce short‐term anxiety in pregnancy. Second trimester routine ultrasound may reduce the numbers of inductions for post‐maturity. Second trimester ultrasound may improve the detection of major fetal abnormalities and increases termination of pregnancies with fetal abnormality. It may reduce the number of undetected twin pregnancies by 24 weeks. This accords with observational data. This review may underestimate the effect size in modern practice because the trials mostly date from relatively early in the development of the ultrasound technology and many participants in the control arms also underwent ultrasound. The evidence that neither first nor second trimester routine ultrasound alters other maternal or fetal outcomes may also be an effect of the relatively low event rates of these outcomes or whether intervention is offered or not, based on the information provided by ultrasound. First and second trimester ultrasound did not appear to increase or decrease the numbers of caesarean section and this may well be because many indications for caesarean section only become apparent in the third trimester of pregnancy.

Implications for research

Future trials comparing routine with selective or no ultrasound will be difficult for two reasons. Firstly, ultrasound examinations are already widely used. Our observation of the large number of scans in the control groups in the trials we reviewed suggests that this problem affected past trials in addition. Secondly, the sample sizes of any trial which had a reasonable chance of detecting a clinically important effects on perinatal death, or any other substantive outcome, would need to be huge. For example, assuming a control group estimate of perinatal death of 3 per 1000, the majority of these being due to prematurity would not be altered by accurate dating. At most, accurate dating might reduce mortality to 2 per 1000. A trial to test such a hypothesis would require 39,000 per group (alpha 0.05, beta 0.2). A trial to test a more plausible hypothesis that perinatal mortality fell from 3 per 1000 to 2.8 per 1000 would require 1,135,000 participants per group. Such a trial is not feasible. Future research on the effectiveness of scanning before 24 weeks could therefore be based on observational data.

Acknowledgements

This project was supported by the National Institute for Health Research (NIHR), via Cochrane Infrastructure funding to Cochrane Pregnancy and Childbirth. The views and opinions expressed therein are those of the authors and do not necessarily reflect those of the Evidence Synthesis Programme, the NIHR, National Health Service (NHS) or the Department of Health and Social Care.

We thank Mrs Therese Dowswell and Dr Theresa Lawrie from the Evidence‐Based Medicine Consultancy Ltd in Bath, United Kingdom (e-bmc.co.uk) for their support with the review. Their help with data extraction, data entry into Revman and GRADEpro and offering their methodological expertise was greatly appreciated.

This review is supported by funding from the UNDP‐UNFPA‐UNICEF‐WHO‐World Bank Special Programme of Research, Development and Research Training in Human Reproduction (HRP) to Cochrane Pregnancy and Childbirth (University of Liverpool). HRP supports and coordinates research on a global scale, synthesizes research through systematic reviews of literature, builds research capacity in low‐ and middle‐income countries and develops dissemination tools to make efficient use of ever‐increasing research information. In addition to its cosponsors, the International Planned Parenthood Federation (IPPF) and UNAIDS are both members of HRP’s governing body.

As part of the pre‐publication editorial process, this review has been commented on by four peers (an editor and three referees who are external to the editorial team), a member of Cochrane Pregnancy and Childbirth's international panel of consumers and the Group's Statistical Adviser. The authors are grateful to the following peer reviewers for their time and comments:

Anthony Shanks, MD, Department of Obstetrics and Gynecology, Indiana University School of Medicine
Suneet P. Chauhan, M.D., Hon.D.Sc., Principal Investigator, Eunice Kennedy Shriver NICHD Maternal‐Fetal Medicine Units Network; Professor, McGovern Medical School at UTHealth; Adjunct Professor, Bioengineering Department, Rice University
Fabricio da Silva Costa, Maternal Fetal Medicine Unit, Gold Coast University Hospital; School of Medicine, Griffith University, Gold Coast, Australia

Appendix 1. Search terms for ICTRP and ClnicalTrials.gov

(each line will be run separately)

ultrasound AND pregnancy AND randomised

ultrasound AND pregnancy AND randomized

ultrasound AND pregnant AND randomised

ultrasound AND pregnant AND randomized

ClinicalTrials.gov

Advanced search

Interventional Studies | pregnancy | ultrasound

Data and analyses

Comparison 1.

No. of studies	No. of participants	Statistical method	Effect size
1	634	Risk Ratio (M‐H, Fixed, 95% CI)	0.80 [0.65, 0.99]
1	648	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.55, 1.73]
2	1472	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.23, 2.31]
1	824	Risk Ratio (M‐H, Fixed, 95% CI)	0.52 [0.10, 2.82]
2	1111	Risk Ratio (M‐H, Fixed, 95% CI)	0.84 [0.57, 1.24]
1	463	Risk Ratio (M‐H, Fixed, 95% CI)	2.96 [0.12, 72.32]
1	9	Risk Ratio (M‐H, Fixed, 95% CI)	0.53 [0.03, 8.19]
1	9	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.05, 16.36]
1	218	Risk Ratio (M‐H, Fixed, 95% CI)	2.74 [0.11, 66.51]
3	1253	Risk Ratio (M‐H, Fixed, 95% CI)	1.27 [0.99, 1.61]
3	1474	Risk Ratio (M‐H, Random, 95% CI)	0.83 [0.50, 1.37]
1	463	Risk Ratio (M‐H, Fixed, 95% CI)	0.73 [0.49, 1.09]
1	463	Risk Ratio (M‐H, Fixed, 95% CI)	0.99 [0.14, 6.95]
1	602	Risk Ratio (M‐H, Fixed, 95% CI)	0.89 [0.45, 1.76]
1	602	Risk Ratio (M‐H, Fixed, 95% CI)	0.77 [0.55, 1.08]
1	824	Risk Ratio (M‐H, Fixed, 95% CI)	0.84 [0.50, 1.39]
1	594	Risk Ratio (M‐H, Fixed, 95% CI)	2.01 [0.99, 4.08]

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Comparison 1: First trimester routine versus selective ultrasound, Outcome 10: Caesarean section rate

Comparison 2

No. of studies	No. of participants	Statistical method	Effect size
3	17918	Risk Ratio (M‐H, Fixed, 95% CI)	0.98 [0.81, 1.20]
7	33911	Risk Ratio (M‐H, Fixed, 95% CI)	0.88 [0.69, 1.12]
3	11316	Risk Ratio (M‐H, Fixed, 95% CI)	0.68 [0.42, 1.11]
1	9310	Risk Ratio (M‐H, Fixed, 95% CI)	0.92 [0.78, 1.08]
3	29584	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.43, 1.82]
5	274	Risk Ratio (M‐H, Fixed, 95% CI)	0.05 [0.02, 0.16]
3	135	Risk Ratio (M‐H, Fixed, 95% CI)	0.10 [0.01, 1.74]
2	16520	Mean Difference (IV, Fixed, 95% CI)	0.90 [0.84, 0.96]
3	10306	Mean Difference (IV, Random, 95% CI)	0.08 [‐0.30, 0.46]
5	16836	Risk Ratio (M‐H, Random, 95% CI)	1.08 [0.91, 1.27]
5	22193	Risk Ratio (M‐H, Fixed, 95% CI)	1.05 [0.98, 1.12]
6	24174	Risk Ratio (M‐H, Random, 95% CI)	0.48 [0.31, 0.73]
5	23267	Risk Ratio (M‐H, Random, 95% CI)	0.75 [0.56, 1.00]
3	29454	Risk Ratio (M‐H, Fixed, 95% CI)	1.32 [0.84, 2.07]
2	387	Risk Ratio (M‐H, Random, 95% CI)	3.45 [1.67, 7.12]
4	26893	Risk Ratio (M‐H, Fixed, 95% CI)	2.36 [1.13, 4.93]
1	15281	Risk Ratio (M‐H, Fixed, 95% CI)	1.03 [0.78, 1.36]
3	25396	Risk Ratio (M‐H, Fixed, 95% CI)	0.79 [0.48, 1.28]
6	17484	Risk Ratio (M‐H, Fixed, 95% CI)	0.92 [0.84, 1.01]
5	23177	Mean Difference (IV, Random, 95% CI)	16.79 [‐6.44, 40.03]
5	16666	Risk Ratio (M‐H, Random, 95% CI)	0.89 [0.69, 1.15]
1	990	Risk Ratio (M‐H, Fixed, 95% CI)	0.75 [0.36, 1.56]
1	964	Risk Ratio (M‐H, Fixed, 95% CI)	1.47 [0.92, 2.35]
1	603	Risk Ratio (M‐H, Fixed, 95% CI)	0.77 [0.44, 1.34]

Comparison 3

No. of studies	No. of participants	Statistical method	Effect size
1	47403	Risk Ratio (IV, Fixed, 95% CI)	1.08 [0.94, 1.24]
1	11680	Risk Ratio (IV, Fixed, 95% CI)	1.03 [0.89, 1.19]
1	46904	Risk Ratio (IV, Fixed, 95% CI)	1.03 [0.90, 1.18]
1	46904	Risk Ratio (IV, Fixed, 95% CI)	0.99 [0.94, 1.04]
1	46768	Risk Ratio (IV, Fixed, 95% CI)	0.92 [0.55, 1.55]
1	45974	Risk Ratio (IV, Fixed, 95% CI)	0.99 [0.86, 1.14]
1	47312	Risk Ratio (IV, Fixed, 95% CI)	1.01 [0.90, 1.13]

Comparison 4

No. of studies	No. of participants	Statistical method	Effect size
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.57, 3.14]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	1.67 [0.40, 6.94]
1	1073	Risk Ratio (M‐H, Fixed, 95% CI)	1.33 [0.30, 5.92]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	2.00 [0.18, 21.99]
1	11	Risk Ratio (M‐H, Fixed, 95% CI)	0.17 [0.01, 2.92]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	0.97 [0.76, 1.24]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	1.17 [0.39, 3.45]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	1.50 [0.25, 8.94]
1	1062	Risk Ratio (M‐H, Fixed, 95% CI)	1.09 [0.74, 1.61]

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Characteristics of studies

Characteristics of included studies [ordered by study id].


Methods	Randomised controlled trial. Individual randomisation.
Participants	25 general practices providing antenatal care in Trondheim, Norway Inclusion criteria: women attending for antenatal care before 18 weeks’ gestation. Exclusion criteria: women found to not be pregnant, not willing to participate, induced abortion before randomisation
Interventions	Experimental intervention: (510 women). Ultrasound examinations in the 19th and 32nd weeks of pregnancy. The aim of the 19 week scan was to determine the number of fetuses, locate the placenta, measure fetal biparietal diameter to assess gestational age and predict expected date of delivery. The second scan assessed biparietal diameter, the mean abdominal diameter, final placental location and fetal presentation. 67 women had additional scans. Comparison intervention: (499 women). Routine antenatal care with selective scan (41 women were referred for scans)
Outcomes	Spontaneous abortion, hospital admission, suspected IUGR (leading to hospital admission). A fetal biparietal diameter 1 standard deviation below the mean growth curve was used to discriminate between normal growth and IUGR. Third trimester bleeds, induction of labour, twin pregnancy, birthweight, body measurements of the newborn, transfer to neonatal unit, perinatal death.
Notes	Study dates: May 1979 to September 1981 Study funding sources: County public health office Study authors’ declarations of interest: not reported Ethical approval obtained: not reported, it was mentioned that women gave oral consent Study prospectively registered: not reported There were no established growth curves for mean abdominal diameter at the onset of the study, therefore these measurements were not consistently used to detect growth retardation.


Random sequence generation (selection bias)	Unclear risk	Reported as randomised controlled trial
Allocation concealment (selection bias)	Unclear risk	Described as the sealed envelope method but no other details provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care
Blinding of outcome assessment (detection bias) All outcomes	High risk	Outcome assessment known to staff although it was stated that newborn outcomes were assessed by staff unaware of allocation, so these may have been at lower risk of bias
Incomplete outcome data (attrition bias) All outcomes	High risk	54 of 510 (10.6%) women in the screening group failed to attend the first scan and an additional 33 (7.2%) failed to attend the second screening scan.
Selective reporting (reporting bias)	Unclear risk	No prespecified outcomes. Not registered.
Other bias	Low risk	Women were described as similar at baseline (and preliminary data supports this).


Methods	Randomised controlled trial. Individual randomisation.
Participants	The study was carried out in the clinics of 3 obstetricians at Queen Charlotte’s Maternity Hospital London, UK Inclusion criteria: 1095 women attending for antenatal care booking visit. Women with pregnancy loss were not included in the analysis. Exclusion criteria: no signs of fetal life on first ultrasound. 1062 women included in the analysis.
Interventions	Experimental intervention: number of women randomised not clear, but 531 included in the analysis. Ultrasound examination at 16 weeks' gestation and these women had the ultrasound report in their clinical notes (revealed to staff providing care). The estimated date of delivery was revised if the BPD indicated a > 2 weeks difference. Control intervention: number of women randomised not clear, but also 531 included in the analysis. Ultrasound examination at 16 weeks' gestation. Results of the 16 week ultrasound retained by the ultrasound department (i.e. women in the control group DID NOT have the ultrasound report in their antenatal care notes (concealed to staff providing care). If the obstetrician had any concerns they could request a copy of the report; this happened for 161 women (30%).
Outcomes	Non viable fetus, multiple pregnancy, perinatal death, induction of labour, birthweight, Apgar score at 1 minute
Notes	Study dates: not reported Study funding sources: not reported Study authors’ declarations of interest: not reported Ethical approval obtained: not reported Study prospectively registered: not reported


Random sequence generation (selection bias)	High risk	“divided... according to the last digit of the hospital number”
Allocation concealment (selection bias)	High risk	“divided... according to the last digit of the hospital number”
Blinding of participants and personnel (performance bias) All outcomes	High risk	“only... ended in an even digit had the actual results entered in their notes”. The estimated date of delivery from last menstrual period was revised if the BPD indicated a > 2 weeks difference, which was made aware to staff. Staff would be aware of allocation. It is not clear if women were aware. (It was not reported whether women consented to randomisation)
Blinding of outcome assessment (detection bias) All outcomes	High risk	The estimated date of delivery was revised if the BPD indicated a > 2 weeks difference, which was made aware to staff.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Women with pregnancy loss were not included in the analysis, although results were available for most of the sample 1062/1095
Selective reporting (reporting bias)	High risk	Results not reported fully or by randomisation group. No prespecified outcomes. Not registered.
Other bias	High risk	There was considerable protocol deviation. 30% of the control group had results revealed which makes interpretation of results more difficult. Baseline characteristics were not described.


Methods	Randomised controlled trial. Individual randomisation.
Participants	15 participating family doctors and 4 obstetricians providing care as part of Heath Care Corporation of St John’s, Newfoundland, Canada serving a mainly white population. Inclusion criteria: women between the ages of 16 and 40 years in the first trimester of pregnancy, deemed to be low‐risk singleton pregnancy presenting to the centre during the study period. Exclusion criteria: women who had an indication for a first trimester ultrasound or already had an ultrasound examination, known multiple pregnancy, under 19 years old with no guardian present, or non consenting
Interventions	218 women with singleton pregnancies were randomised, 10 women assigned to the intervention group and 12 to the control group had early pregnancy loss or were otherwise lost to follow up Experimental intervention: (114 randomised, 104 data available). Early ultrasound and clinical pelvic examination between 8‐12 weeks to accurately estimate gestational age by ultrasound measurement of crown‐rump length If the measurement of gestational age differed by 5 days or more from the last menstrual period estimate the expected date of delivery was revised. Comparison intervention: (104 randomised, 92 data available). Routine antenatal care at the first visit. Women in both the intervention and control group had a routine second trimester ultrasound at 19 weeks.
Outcomes	Primary outcome was induction of labour for suspected post‐term pregnancy. The numbers undergoing caesarean section were also reported
Notes	Study dates: women were recruited between 31.12.1999 and 11.04.2002 Study funding sources: not reported Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: not reported


Random sequence generation (selection bias)	Low risk	Computer‐generated random number tables
Allocation concealment (selection bias)	Low risk	Opaque envelopes containing assignment were prepared by an administrator. Envelopes were sequentially numbered.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The estimated due date from last menstrual period was revised if the one derived by crown‐rump length differed more than 5 days.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care
Incomplete outcome data (attrition bias) All outcomes	Low risk	Loss to follow up similar in the 2 groups
Selective reporting (reporting bias)	High risk	No prespecified outcomes. Not registered. Results not fully reported.
Other bias	Unclear risk	Characteristics appeared similar at baseline and other bias was not apparent.


Methods	Randomised controlled trial. Individual randomisation.
Participants	Tertiary level hospital in Adelaide, Austalia Inclusion criteria: women were recruited at their first antenatal visit if this visit was before 17 weeks’ gestation, they had no previous ultrasound scans in this pregnancy and were expected to give birth at the study hospital. Exclusion criteria: women were excluded if they had an indication for an ultrasound at their first antenatal visit.
Interventions	648 women were recruited to the trial. Women were enrolled by telephone randomisation to either the intervention arm or the control arm. Experimental intervention: (321 women) Ultrasound examination at their first antenatal visit. The assessment included fetal cardiac activity, estimation of gestational age, limited assessment of fetal morphology and the number of fetuses present. The mean gestational age of these first visit scans was at 10.7 weeks (SD 2.7 weeks). The report of the scan was available to caregivers to plan timing of maternal serum screening bloods and the 18‐20 weeks ultrasound morphology scan. (The report was not made available to the person carrying out the 18‐20 week scan.) Comparison intervention: (327 women). Routine antenatal care, no scan at the first visit. Women in both groups completed an anxiety questionnaire at the end of their first antenatal visit. Women in both the intervention and control group had a routine 18‐20 week ultrasound.
Outcomes	Adjustment for gestational age, perinatal loss, anxiety at the end of the first visit (measured on a Likert scale), TOP for any reason, caesarean section (The primary outcomes (used in power calculation) in the study were adjustment of the estimated due date of 10 days or more on the basis of their morphology scan and women booked for serum screening blood tests and morphology scans at inappropriate gestational ages. Secondary outcomes included time of diagnoses of anomaly, nonviable pregnancy, multiple pregnancy, other scans performed, and smoking at 36 weeks’)
Notes	Study dates: recruitment 1991‐1995 Study funding sources: not reported Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: registered during recruitment phase with International Registry of Perinatal Trials


Random sequence generation (selection bias)	Low risk	Randomisation schedule was generated using random number tables with stratification by parity. 1: 1 ratio
Allocation concealment (selection bias)	Low risk	Telephone randomisation service. The next in a consecutively numbered sealed, opaque envelopes were opened by the research assistant in the telephone service. Envelopes containing allocations were prepared by a researcher not involved in the clinical care setting.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Staff carrying out 18‐20 week scans did not have access to earlier reports, but it was not clear whether they were aware that an earlier scan had been performed. Staff may have been aware of allocation when administering anxiety questionnaires.
Incomplete outcome data (attrition bias) All outcomes	Low risk	Primary analysis was on an ITT basis. Data available for 602/648 women randomised (93%). There were some missing data (22/321 women in the intervention group and 24/327 in the control group had no 18‐20 week scan data). Missing data wee mainly accounted for by miscarriage which was balanced across groups.
Selective reporting (reporting bias)	Unclear risk	The outcomes regarding anxiety were not fully explained and were not clear. Trial was registered and all relevant outcomes stated were reported in findings including non‐significant results.
Other bias	Low risk	There was no evidence of differences in baseline characteristics. It was not reported how many of the women attending the hospital were eligible for inclusion which may affect generalisability.


Methods	Randomised controlled trial. Individual randomisation.
Participants	All women attending for their first antenatal care visit at the clinics of 35 general practitioners in Alesund, Norway. The study population is representative for pregnant women who lived in this region of Norway at that time. Inclusion criteria: women living in Alesund, Norway Exclusion criteria: non‐consenting
Interventions	In total 1628 women were randomised. Experimental intervention: (825 women). Ultrasound examinations at 18th and 32th weeks of pregnancy. At 18th weeks the number of fetuses and the position of the placenta were recorded. A general examination of the fetus was carried out and biparietal diameter was measured to estimate gestational age. At 32 weeks biparietal diameter was measured to assess growth, placental position and fetal presentation were noted. If fetal growth restriction was suspected or presentation was breech women were offered a further scan at 36 weeks. In addition women were offered scans at any time if clinically indicated (on average women in the intervention group had 2.5 scans). Comparison intervention: (803 women). Routine antenatal care with selective scan. 481/727 women with singleton pregnancies did not undergo scans.
Outcomes	Sample size calculation on post‐term inductions of labour, data collected on hospital admissions, infant size and condition at birth, perinatal mortality, twin pregnancies diagnosed before 26 weeks.
Notes	Study dates: May 1979 to September 1981 Study funding sources: Alesund Central Hospital and National Institute of Health Study authors’ declarations of interest: not reported Ethical approval obtained: not reported. Women gave oral consent. Study prospectively registered: not reported


Random sequence generation (selection bias)	Unclear risk	Method of sequence generation not stated
Allocation concealment (selection bias)	Unclear risk	Described as the sealed envelope method but no other details provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care
Blinding of outcome assessment (detection bias) All outcomes	High risk	In the intervention group the gestational age was calculated on the basis of biparietal diameter. Women had a 32 weeks scan to assess fetal growth. Clinical staff would be aware of the results, which can affect clinical management and possibly other aspects of care
Incomplete outcome data (attrition bias) All outcomes	Low risk	Preliminary results from the trial were published as a letter in 1984 and reported a study population of 1628 women, of whom 809 were randomised to ultrasound screening and 819 were controls. In a later follow‐up of the children at 8 or 9 years of age, it was disclosed that 825 women were randomised to screening and 803 women were randomised to be controls. Loss was balanced between groups, there were some missing data (< 10%)
Selective reporting (reporting bias)	Low risk	Although study protocol is not available there was a re‐analysis of data reported previously and appears accurate and complete
Other bias	Unclear risk	Groups mainly appeared balanced at baseline but more women in the control group were non‐smokers (69% vs 64%) (P value 0.02)


Methods	Randomised controlled trial. Stratified by participating practice size.
Participants	Women attending 8 family physicians and eight hospital obstetricians at the University of Missouri Hospital and Clinics and Boone Hospital Center Columbia, Missouri, USA Inclusion criteria: women planning to continue pregnancy to term and planning delivery with 1 of the participating physicians, less than 18 weeks’ gestation. Exclusion criteria: pre‐existing indication for ultrasound (unknown gestational age, size/date discrepancy of 4 weeks, previous stillbirth, diabetes, chronic hypertension, chronic renal disease, etc.), planned amniocentesis, repeat caesarean section, gestational age already confirmed on ultrasound, suspected molar/ectopic pregnancy, threatened/inevitable miscarriage, fetal death, presence of IUD More than half of the women screened for inclusion were not eligible. 915/2171 screened were randomised. Half of the women excluded did not know menstrual dates or had already had a dating scan.
Interventions	Experimental intervention: (459 women randomised, 402 available for analysis). Early ultrasound examination between 10‐12 weeks’ gestation (but up to 18 weeks) to assess gestational age (using crown‐rump length (up to 13 weeks), biparietal diameter or femur length (after 13 weeks), number of fetuses, fetal viability and uterine or fetal abnormalities. 337 of the women in the group received the scheduled routine ultrasound. Comparison intervention: (456 randomised, 413 available for analysis) Routine antenatal care with selective scan. 96 women (23.9%) received a selected ultrasound scan between 10‐18 weeks.
Outcomes	Change in estimate of gestational age; induction of labour (for post‐dates pregnancy or other indication), perinatal death, adverse perinatal outcome, diagnoses of twin pregnancies before 24 weeks/ before delivery
Notes	Study dates: 01.09.1984 to 31.05.1986 Study funding sources: Biomedical Research Support grant from the Department of Health and Human services, advanced technology Laboratories, Bothell, Washington, and the Robert Wood Johnson Family Practice Fellowship Program, University of Missouri Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: not reported


Random sequence generation (selection bias)	Unclear risk	It was not clear how the randomisation sequence was generated, A system if blocks if 4 was used to assure a balanced distribution if patients in the screened and usual‐care groups for each practice. It was not clear how many women were randomised at each of the participating clinics.
Allocation concealment (selection bias)	Unclear risk	Randomisation cards were placed in sequentially numbered sealed opaque envelopes. It was not clear if all envelopes were accounted for. The study used a Zelen post randomisation method and women decided to take part already knowing their assignment.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Gestational age was calculated using (using crown‐rump length (up to 13 weeks) or biparietal diameter or femur length (after 13 weeks) in the intervention group. The physicians were provided with the ultrasound results.
Incomplete outcome data (attrition bias) All outcomes	High risk	Of the 2171 screened patients 915 were eligible and had not exclusion criteria. Data were available for 815/915 randomised. 337/402 in the experimental group had their scheduled ultrasound. 96/413 in the control group had an indicated ultrasound scan between 10‐18 weeks' gestation.
Selective reporting (reporting bias)	Unclear risk	Trial not registered. Outcomes in the methods section fully reported.
Other bias	High risk	There were protocol deviations with women not receiving the planned intervention. Baseline characteristics were similar although there were more nulliparous women in the intervention group (56.5%) vs controls (48.8%) and the number of twin pregnancies was greater in the control group.


Methods	Randomised controlled trial. Individual randomisation.
Participants	Antenatal clinic and ultrasound unit within the area served by Tygerberg Hospital; a tertiary referral centre, South Africa. Inclusion criteria: women without risk factors for congenital anomalies referred for ultrasonography between 18 and 24 weeks’ gestation. Women with uncertain dates of last menstrual period included. Exclusion criteria: women over 37 years of age, having had previous ultrasound in this pregnancy, women with increased risk of congenital abnormalities, diabetes mellitus or rhesus sensitisation.
Interventions	Experimental intervention: (496 women randomised). Ultrasound examination between 18 and 24 weeks Comparison intervention: (492 women randomised). Routine antenatal care with selective scan
Outcomes	Adverse perinatal outcome and use of antenatal and neonatal services, health service costs
Notes	Study dates: November 1991 to August 1992 Study funding sources: not reported Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: not reported


Random sequence generation (selection bias)	Unclear risk	Reported as randomised controlled trial
Allocation concealment (selection bias)	Unclear risk	Described as the sealed envelope method but no other details provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	'clinicians received a report on the ultrasonographic findings'. Women would be aware of allocation.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded “clinicians received a report on the ultrasonographic findings …and decided on all further management"
Incomplete outcome data (attrition bias) All outcomes	Low risk	79 women were excluded as “not pregnant” or “lost to follow up” Similar numbers of patients excluded in both groups for not pregnant or lost for follow up.
Selective reporting (reporting bias)	Unclear risk	Trial not registered. Outcomes in the methods section fully reported.
Other bias	Low risk	Other bias not identified.


Methods	Cluster‐randomised controlled trial. Multi‐centre trial in 58 sites (clusters) in 5 countries: Pakistan (10), Kenya (12), Zambia (10), Democratic Republic of Congo (8), and Guatemala (18). Intervention and control clusters were stratified by country, and factors such as historic perinatal mortality rates and logistic factors such as travel time to Emergency Obstetric and Neonatal Care facilities were also taken into account. Each cluster was defined by a health centre and its catchment area with approximately 500 births per year. The 58 clusters (29 intervention and 29 control) were in mainly rural areas.
Participants	46,904 women delivered in the cluster areas over the study period. Inclusion criteria: all pregnant women attending clinics able to give informed consent and living in the study cluster at or after 18 weeks' gestation. Exclusion criteria: women in labour
Interventions	Experimental intervention: (24,008 women in 29 clusters). This was a complex intervention involving training health workers (nurses, midwives and clinical officers) to perform ultrasound at 16‐22 and 32‐36 weeks' gestation. Women identified with complications were to be referred to hospital. There were also community sensitization activities to inform women of the ultrasound clinics. A further component of the intervention was training provided to staff in referral hospitals to provide care in major obstetric and neonatal emergencies (such as newborn resuscitation). 2 routine ultrasound examinations were offered to all intervention cluster pregnant women at 16–22 weeks' and 32‐36 weeks' gestation. Control intervention: (22,896 women in 29 clusters). Routine care. No study ultrasound examinations or community interventions
Outcomes	The primary study outcome was a composite of maternal mortality, maternal near‐miss mortality, stillbirth, and neonatal mortality. Other outcomes: maternal morbidity, intrauterine growth restriction‐related mortality. Rate of prenatal care utilization, delivery in a risk‐appropriate setting
Notes	Study dates: July 2014 to May 2016 Study funding sources: Bill and Melinda Gates Foundation, Eunice Kennedy Shriver National Institute of Child Health. Ultrasound equipment supplied by GE healthcare Study authors’ declarations of interest: none declared Ethical approval: committees including University of Washington, Columbia University, Research Triangle Institute (Durham, NC), University of Zambia, Kinshasa School of Public Health (DRC), Moi University (Kenya), Aga Khan University (Pakistan), Francisoc Marroquin University (Guatemala) Study prospectively registered: yes, at clinicaltrials.gov


Random sequence generation (selection bias)	Low risk	An external coordinating centre generated the random assignment of sites. Sites were stratified by country and other factors such as baseline perinatal mortality.
Allocation concealment (selection bias)	Low risk	Randomisation was conducted externally.
Blinding of participants and personnel (performance bias) All outcomes	High risk	No attempt at blinding.... “nature of this intervention precluded masking of the study intervention”. The trialists recognised the “possibility of modifying the intervention through over attentive monitoring”
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	“primary outcome data….were collected by MNHR administrators” Outcome assessment may have been affected by lack of blinding (e.g. identification of near miss events)
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	“lost‐to‐follow up rates similar between….groups” There were discrepancies in the number of clusters and in some of the outcome data reported in the protocol and subsequent papers. These discrepancies were not explained.
Selective reporting (reporting bias)	Low risk	The trial was registered and main objectives reported. Analyses took account of cluster design effect.
Other bias	Unclear risk	There was some protocol deviation. In the intervention clusters 77.6% of women received at least one study ultrasound. There was considerable variation in different settings with regard to ultrasound use in control groups (95% in Pakistan vs < 5% in African countries). Other considerations: clusters were stratified by country and took account of baseline differences between settings. However, there was huge variation between cluster sites in terms of baseline mortality rates and maternity care provision and utilisation. Stillbirth rates ranged between 22 to 54 per 1000 and neonatal mortality between 16 to 45 per 1000 infants. Baseline caesarean section rates ranged from 0.1% in Democratic Republic Kongo to 11.4% in Guatemala. Birth location and birth attendant also varied considerably. Despite adjustment to take account of cluster design, these large variations between sites means that overall results are more difficult to interpret.


Methods	Randomised controlled trial. Individual randomisation.
Participants	20 collaborating general practices and a district teaching hospital in the United Kingdom Inclusion criteria: women attending their GP practice, in the first trimester of pregnancy, no obstetric indication for a first trimester ultrasound examination. Exclusion criteria: indication for a first trimester scan
Interventions	Experimental intervention: (233 women randomised). Early ultrasound examination to measure the crown‐rump length between 8 and 12 weeks of gestation. Comparison intervention: (230 women randomised). Routine care. Gestational age was based on last menstrual period. Women in both arms were offered an anomaly ultrasound examination at 20 weeks of gestation.
Outcomes	Induction of labour for post‐dates.
Notes	Study dates: February 1999 to October 2001 Study funding sources: NHS Executive South East Study authors’ declarations of interest: none declared Ethical approval obtained: yes Study prospectively registered: registered in metaRegister of controlled trials


Random sequence generation (selection bias)	Low risk	Randomisation in blocks of 6.
Allocation concealment (selection bias)	Low risk	Participating general practices were provided with a series of consecutively numbered, sealed, opaque envelopes randomised in blocks of six, which allocated the women to the ‘scan’ or ‘no‐scan’ group.
Blinding of participants and personnel (performance bias) All outcomes	High risk	The estimated due date was recalculated if the scan dates differed by more than 5 days with the menstrual dates. The estimated due date was entered into the patient’s obstetric notes, and all subsequent management decisions were based on this assessment of gestational age.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Multiple gestations were disclosed as were suspected structural fetal anomalies with referral to the prenatal diagnosis unit. Nonviable or ectopic pregnancies were managed appropriately.
Incomplete outcome data (attrition bias) All outcomes	Low risk	4 women in each group lost to follow up. 9 women in scan arm had non trial scan; 21 in no scan arm had non trial scan
Selective reporting (reporting bias)	Low risk	Trial was registered and expected outcomes were reported
Other bias	High risk	Trial was stopped early.


Methods	Randomised controlled trial. Individual randomisation.
Participants	92 obstetric practices and 17 family practices across 6 states in the USA. Inclusion criteria: English speaking “low‐risk” pregnant women who were aged 18 years or older. Last menstrual period known within 1 week. Gestational age < 18 weeks. No plans to change care provider. Exclusion criteria: previous ultrasonography during this pregnancy, previous stillbirth, irregular menstrual cycle, last menstrual period induced by an oral contraceptive agent, fertility‐drug use in current cycle, discrepancy between size and dates > 3 weeks, previous small‐for‐gestational‐age infant, diabetes mellitus, chronic hypertension, chronic renal disease, pelvic mass, fetal death, ectopic pregnancy, molar pregnancy, multiple gestation, planned termination of pregnancy, planned amniocentesis, planned cervical cerclage, planned ultrasonography for reasons other than screening
Interventions	Experimental intervention: (7812 randomised, 7617 analysed). Ultrasound examinations between 15‐22 weeks and 31‐35 weeks for placental location, amniotic‐fluid volume, uterine and adnexal pathology, the number of fetuses, and sonographic biometry of the fetus (biparietal diameter, head circumference, abdominal circumference and femur length), as well as a detailed anatomical survey of the intracranial anatomy, spine, heart (4‐chamber view), stomach, cord insertion, diaphragm, kidneys, bladder, and extremities of the fetus. Comparison intervention: (7718 randomised, 7534 analysed). Routine antenatal care with selective scan (i.e. only when it was ordered by a physician for medical reasons that developed after randomisation).
Outcomes	Adverse perinatal outcome (fetal death, neonatal death, neonatal morbidity)
Notes	Study dates: 1. November 1987 to 31 May 1991 Study funding sources: supported under cooperative agreements (HD 21017, HD 19897, and HD 21140) with the National Institute of Child Health and Human Development Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: not reported


Random sequence generation (selection bias)	Low risk	“microcomputer‐based randomisation sequence after stratification by practice site”
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	High risk	The findings were reported to the woman's physician.
Blinding of outcome assessment (detection bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care.
Incomplete outcome data (attrition bias) All outcomes	Low risk	'131 women in the screened group and 121 women in the control group were lost to follow up, primarily because of patient relocation'. The reasons for which women were lost to follow‐up, and their frequency, were similar in the ultrasound‐screening and control groups. In addition, the women lost to follow‐up in the two groups were similar with respect to their base‐line characteristics. “7617 in the screened group and 7534 in the control group, were analysed”
Selective reporting (reporting bias)	High risk	No prespecified outcomes. Not registered. Individual adverse outcomes not reported.
Other bias	High risk	Timing of fetal deaths not reported.


Methods	Randomised controlled trial. Individual randomisation.
Participants	Women attending one of 64 maternal health centres in the catchment area of Helsinki University Central Hospital, Finland Inclusion criteria: pregnant women attending the health centre, before the 20th week of pregnancy irrespective of having had a previous scan in this pregnancy Exclusion criteria: women who were not pregnant, miscarriage before 22 weeks/ termination of pregnancy before screening began
Interventions	Experimental intervention: (4691 women randomised, 4353 analysed) ultrasound screening between 16 and 20 gestational week Comparison intervention: (4619 women randomised, 4309 analysed) routine antenatal care with selective scan
Outcomes	Detection of major fetal abnormality, antenatal use of medical services, rates of obstetric procedures, fetal outcome
Notes	Study dates: recruitment April 1986 to November 1987; Births: September 1986 to July 1988 Study funding sources: Helsinki University Central hospital fund and Academy of Finland Study authors’ declarations of interest: not reported Ethical approval obtained: not reported Study prospectively registered: not reported


Random sequence generation (selection bias)	Unclear risk	Reported as randomised controlled trial.
Allocation concealment (selection bias)	Unclear risk	Described as the sealed envelope method but no other details provided
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not blinded
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not blinded
Incomplete outcome data (attrition bias) All outcomes	Low risk	“318 women did not attend ultrasound screening at the two study hospitals” “drop outs between randomisation and delivery were equally distributed between the groups” “4 women lost to follow up because of incomplete identification or moving abroad” “non‐attenders were included and analyzed as part of the screening group"
Selective reporting (reporting bias)	High risk	Study not prospectively registered. Pre‐specified outcomes were antenatal use of medical services, rates of obstetric procedures, and fetal outcomes.
Other bias	High risk	In the control group 77% underwent a scan at anytime in pregnancy, in 43.5% that scan was also between 16‐20 weeks' gestation.


Methods	Open cluster‐randomised controlled trial.
Participants	Study conducted in a district hospital (Dr Yusuf Dadoo Hospital) and regional referral hospitals (Leratong Hospital) in Western Gauteng, South Africa. These 2 hospitals serve a predominantly black working class population who depend on free state‐funded maternity care facilities. Inclusion criteria: low‐risk pregnancies at 18–23 weeks by clinical estimation who planned to deliver at either, of the two hospitals above. Women with uncertain menstrual history were included. Exclusion criteria: high‐risk pregnancies, women who already had an ultrasound in this pregnancy. A cluster was defined as all eligible women presenting for prenatal care on a single day. Of 955 women enrolled, 151 (15.7%) were lost to follow up, leaving 804 for analysis
Interventions	All participants who presented on a certain day would be randomised in one cluster to either the intervention group or the control group. Experimental intervention: (416 women randomised). Ultrasound scan at 18‐23 weeks' gestation and referral for additional ultrasound scans by hospital ultrasonographers for clinical indications. Comparison intervention: (388 women randomised). Routine care and referral for ultrasound scans by hospital ultrasonographers for clinical indications.
Outcomes	Induction of labour for post‐term pregnancy and perinatal death. Number of prenatal visits, hospitalisation before onset of labour, detection of fetal abnormalities and neonatal admission rates
Notes	Study dates: June 2002 to May 2004 Study funding sources: not reported Study authors’ declarations of interest: not reported Ethical approval obtained: yes Study prospectively registered: yes


Random sequence generation (selection bias)	High risk	all women presenting…on a single day were defined as a cluster, but this could lead to bias as the next day of presentation could be affected for example by transport (bus routes) or community activities. 'Randomisation was done by blinded selection of cards from a box'.
Allocation concealment (selection bias)	High risk	By blinded selection of cards from a box. Half of the cards were marked A, and half were marked B. If an A was drawn, the cluster was assigned to the USS group, entitling all participants on that morning to an ultrasound scan. Women/staff on different days may have been different and staff would be aware of allocation at the point of randomisation.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Not concealed “ultrasound findings were entered…on prenatal records”
Blinding of outcome assessment (detection bias) All outcomes	High risk	Not concealed “ultrasound findings were entered…on prenatal records”
Incomplete outcome data (attrition bias) All outcomes	Low risk	151 women lost to follow up, 7 excluded due to risk factors identified after enrolment, 416/490 and 388/472 controls followed up
Selective reporting (reporting bias)	Low risk	Study prospectively registered
Other bias	Low risk	Other bias not identified.


Methods	Randomised controlled trial. Individual randomisation.
Participants	19 antenatal clinics run by the South Hospital in Stockholm, Orebro Medical Centre Hospital and Vasteras Central Hospital, Sweden Inclusion criteria: women booking for antenatal care at one of 19 antenatal clinics (run by the South Hospital in Stockholm, Orebro Medical Centre Hospital and Vasteras Central Hospital between October 1985 and March 1987) Exclusion criteria: non‐consenting, booking after 19 gestational weeks, already had a scan, intention to change clinic, fulfilling 1 or more of the predetermined indications for 2nd trimester scan: irregular bleeding pattern, previous multiple pregnancy, severe malformation or perinatal loss, previous small‐for‐gestational age, maternal medical condition including diabetes, kidney disease and hypertension, intention to have amniocentesis, uterus > 4 weeks larger than expected, miscellaneous
Interventions	Experimental intervention: (2482 women). Routine ultrasound screening at 15 weeks (range 13‐19 weeks). Calculation of estimated due date from biparietal diameter. Comparison intervention: (2511 women). Routine antenatal care with selective scan. Estimated due date derived from last menstrual period.
Outcomes	Induction of labour due to post‐maturity Increased mean birthweight of twins/increased length of twin pregnancy
Notes	Study dates: October 1985 to March 1987 Study funding sources: Bank of Sweden Tercentenery Foundation, Research Council of Dalarna, County Council of Kopparberg Follow up study: Research Council of Dalarna, Foundation of Astrid Karlsson, Uppsala University, Foundation of Medical Research and Evaluation in Dalarna Study authors’ declarations of interest: none reported Ethical approval obtained: not reported Study prospectively registered: yes, registered with Oxford database of perinatal trials during recruitment


Random sequence generation (selection bias)	Low risk	The assignments had been enclosed in opaque, sealed envelopes, and then mixed thoroughly before the assignment procedures
Allocation concealment (selection bias)	Unclear risk	Described as the sealed envelope method but no other details provided.
Blinding of participants and personnel (performance bias) All outcomes	High risk	Participants would be aware of assignment at the point of treatment. Clinical staff would be aware of treatment allocation, which would affect clinical management and possibly other aspects of care.
Blinding of outcome assessment (detection bias) All outcomes	High risk	In the intervention group the gestational age was calculated on the basis of biparietal diameter. Clinical staff would be aware of the results, which would affect clinical management and possibly other aspects of care
Incomplete outcome data (attrition bias) All outcomes	Low risk	“32…screening group did not attend for the screening scan”. Loss to follow up in screening group was 52 vs 67 in control group
Selective reporting (reporting bias)	Low risk	Study prospectively registered and main outcomes reported
Other bias	Low risk	Other bias not identified.

Characteristics of excluded studies [ordered by study ID]

Study	Reason for exclusion
	Scans in both arms. Both, in the intervention group and the control group there was a 10 to 14 + 6‐week nuchal scan followed by routine 16–23 week scan. However, the intervention group had an additional 12 to 14 + 6–week detailed scan.
	Scans in both arms between 16 ‐ 24 weeks’ gestation and additional scan in 3rd trimester in the intervention group.
	Intervention was scan 1st trimester screening scan vs 2nd trimester screening scan.
	Both groups had an early scan. Serial scans in 3rd trimester.
	Comparison was 2nd trimester 2‐dimensional (2D) ultrasound vs 2nd trimester 3/4D ultrasound.
	Women were enrolled before 32 weeks and had ultrasound between 32‐37 weeks' gestation
	All women had ultrasound scans but at different not specified schedules.
	Randomised to 2‐dimensional (2D) ultrasound vs 2‐dimensional (2D) plus 4‐dimensional (4D) ultrasound
	In this study first and second trimester screening for Down's syndrome were compared. Both groups had scans.
	Randomised to 2‐dimensional (2D) ultrasound vs 2 dimensional (2D) plus 4‐dimensional (4D) ultrasound
	Randomised to either ultrasound at 18, 20 weeks or 22 weeks.
	All women had 1st trimester scans. Women were randomised to different ultrasound probes for the scan.
	Randomised to various scanning protocols from 16 to 40 weeks.

Characteristics of studies awaiting classification [ordered by study ID]

Methods	Randomised controlled trial
Participants	Low risk pregnant women published as abstract.
Interventions	Two scans versus clinically indicated scan
Outcomes	Follow‐up of children after birth at 6 and 18 months
Notes	Published only as abstract and we have not been able to confirm with the trial authors that the data were from the final analyses. Unsuccessful in attempt to contact two of the authors on 22.9.2020.

Methods	Randomised controlled trial
Participants	Pregnant women before 11 weeks' gestation
Interventions	Early (11 – 14 weeks) ultrasound screen for FA (including nuchal translucency) or control (19‐week scan). All women undergoing termination of pregnancy for fetal abnormality were asked to complete a questionnaire comprising four psychological scales.
Outcomes	Rate of late vs early termination of pregnancy, psychological effects late vs early termination
Notes	Published only as abstract and we have not been able to confirm with the trial authors that the data were from the final analyses. Unsuccessful in attempt to contact the authors. Three authors were contacted between 22.9.2020 and 24.9.2020, without response.

Methods	Randomised controlled trial of routine dating ultrasound in pregnancy
Participants	Pregnant woman booking at John Radcliffe Hospital in Oxford
Interventions	To study the effect of a dating scan on pregnancy outcome
Outcomes	Induction of labour in total and for post term pregnancy, perinatal mortality, multiple pregnancy, maternal hospital admission
Notes	Only the trial registration was published and we were not able to obtain study data from the final analyses from the authors. Unsuccessful in attempt to contact the trial authors on 20.9.2020. The authors also failed to respond to previous request for information from a previous version of this review ( ).

Characteristics of ongoing studies [ordered by study ID]

Study name	Revealed versus concealed criteria for placental insufficiency in unselected obstetric population in late pregnancy: a multicenter randomised controlled trial
Methods	Randomised controlled trial
Participants	Singleton pregnancies after routine second trimester scan (19 + 0 to 22 + 6 weeks of gestation)
Interventions	Cerebroplacental ratio measurement at 37 weeks of pregnancy only taken into account if estimated fetal weight < 10th centile versus cerebroplacental ratio measurement at 37 weeks and labour induction in case of cerebroplacental ratio < 5th centile
Outcomes	Stillbirth, adverse perinatal outcome, fetal growth restriction detection
Starting date	May 2016
Contact information	Frances Figueras, [email protected]
Notes	Author contacted on 7.9.2020, trial still recruiting

Study name	First trimester anomaly scan using virtual reality (VR FETUS study): a randomised clinical trial
Methods	Randomised controlled trial
Participants	Women with an increased risk of carrying a fetus with a congenital anomaly (i.e. high risk) are eligible for participation.
Interventions	The control group receives 'care as usual': a second trimester 2D advanced ultrasound examination. The intervention group will undergo an additional first trimester 2D and 3D VR ultrasound examination.
Outcomes	Detection of fetal anomalies. Quality of life as reflected by psychological burden, and cost‐effectiveness of the first trimester 3D VR ultrasound.
Starting date	01.07.2017
Contact information	Dr M. Rousian, [email protected]
Notes	Authors contacted on 24 September 2020; trial still recruiting, expected to finish September 2021

Study name	Health pregnancy, healthy baby: testing the added benefits of pregnancy ultrasound scan for child development in a randomised control trial
Methods	3‐armed randomised controlled trial
Participants	Mothers and their partners from Soweto, Johannesburg
Interventions	Parents in arm 1 receive a fetal ultrasound scan < 25 weeks during routine antenatal care at tertiary hospitals, and a second standard ultrasound scan at the research site within 2 weeks. Arm 2 participants receive the routine antenatal ultrasound scan and an additional ultrasound scan < 25 weeks at the research site, together with messages to promote parental attachment and healthy child development. Arm 3 participants receive the routine ultrasound scan and 2 additional ultrasound scans at the research site, < 25 weeks and < 36 weeks, together with messages to promote parental attachment and healthy child development.
Outcomes	Child development at 6 months postnatally, infant feeding, parental attachment and interaction, parental mental health and infant growth, assessed at 6 weeks and 6 months
Starting date	03.12.2018
Contact information	Linda Richter, [email protected]
Notes	Authors contacted on 1.10.2020. Final trial data not yet available to share with us.

Differences between protocol and review

The protocol for this review was published in PROSPERO and can be found here . Any differences between our published protocol and the full review are listed below.

The additional non‐prespecified outcomes were requested by the WHO and were therefore added to this review.

Perinatal loss (defined as miscarriage including TOP or intrauterine death after trial entry, or death of a liveborn infant up to 28 days of age or before discharge from hospital). As requested by WHO, we have added the following non prespecified similar outcomes: Perinatal death (fetal death after 24 completed weeks gestation and before 6 completed days of life), perinatal death, excluding those because of lethal malformations, miscarriage (fetal loss before 20 weeks).
Detection of multiple pregnancy before labour (WHO requested outcome)
Birth in a risk‐appropriate setting*
Number of fetal ultrasound scans*
Number of antenatal visits*
Antenatal hospital admission (WHO requested outcome)*
Antenatal care utilisation (4 of more visits) (WHO requested outcome)*
Induction of labour for post‐maturity*
Induction of labour for any cause (WHO requested outcome)
Detection of fetal abnormality before 24 weeks' gestation (WHO requested outcome)
Termination of pregnancy for major anomaly*
Appropriately timed serum screening tests (WHO requested outcome)*
Appropriately timed anomaly scan (18‐22 weeks) (WHO requested outcome)*
Maternal mortality (WHO requested outcome)
Neonatal death (neonatal death during the first 28 days of life) (WHO requested outcome)
Admission to neonatal intensive or special care unit (WHO requested outcome)
Mean birthweight (g) (WHO requested outcome)
Low birthweight (less than 2500 g) (WHO requested outcome)
Small for gestational age (WHO requested outcome)

We had intended that comparisons include: first trimester* routine scan versus selective or no scan and second trimester* routine scan versus no scan and revealed (ultrasound results communicated to both patient and doctor) versus concealed (ultrasound results blinded to both doctor and patient) scan at any time before 24 weeks.

As in all trials women in the control group received receive an ultrasound if clinically indicated, there was no true 'no scan' control group. In some trials the majority of women in the control group had a scan, therefore the comparisons routine scan versus no scan was not applicable. Furthermore there was one trial that took place in low‐and‐middle income countries and not only included a routine scan in the intervention group, but also training of healthcare workers and a referral for complications, and for these reasons, we have added this trial to its own comparison. Therefore the types of interventions covered in this review are:

First trimester* routine scan versus selective scan;
Second trimester* routine scan versus selective scan;
Standard care plus two ultrasounds, training of healthcare workers and referral for complications versus standard care with selective scan

We have added the following outcome to our GRADE methods: 'termination for major fetal abnormality' in place of 'major anomaly before birth'.

* For the assessment of the certainty of evidence (GRADE) we have defined the term 'process outcome'. We have defined a 'process outcome' as a variable that is part of the care pathway which is being guided (and altered) by the ultrasound result. The intervention in a 'process outcomes' is not only the test (ultrasound) but patient management guided by test result (ultrasound finding) and therefore lack blinding does not apply as a reason to downgrade. All other criteria for the assessment of the certainty of evidence apply however.

Contributions of authors

AK: designing the review; coordinating the review, designing search strategies, data extraction, providing a clinical perspective, writing the manuscript

NJ: designing the review, designing search strategies, third review author, providing a clinical perspective, edited the manuscript

JX: providing a methodological perspective, proofread the manuscript

JT: conceiving the review, providing a clinical perspective, proofread the manuscript

JS: data extraction, proofread the manuscript

Sources of support

Internal sources.

No source of support, Other

External sources

This review is supported by funding to Cochrane Pregnancy and Childbirth (University of Liverpool)

Declarations of interest

The authors have nothing to declare.

AK: no conflict of interest.

NJ: no conflict of interest.

JX: no conflict of interest.

JT: no conflict of interest.

JS: no conflict of interest.

References to studies included in this review

Bakketeig 1984 {published data only}.

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RADIUS 1993 {published data only}

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Chen 2008 {published data only}.

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Zhang 2018 {published data only}

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Figueras 2017 {published data only}.

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Pietersma 2018 {published data only}

Pietersma C, Mulders A, Steegers EA, Rousian M. P05.09: virtual reality and feasibility and efficacy of first trimester ultrasound: a randomised controlled trial (VR FETUS study) . Ultrasound in Obstetrics & Gynecology 2018; 52 ( S1 ):154-5. [ Google Scholar ]

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References to other published versions of this review

Whitworth 2015.

Whitworth M, Bricker L, Mullan C. Ultrasound for fetal assessment in early pregnancy . Cochrane Database of Systematic Reviews 2015, Issue 7 . Art. No: CD007058. [DOI: 10.1002/14651858.CD007058.pub3] [ PMC free article ] [ PubMed ] [ CrossRef ] [ Google Scholar ]

IMAGES

Routine first-trimester ultrasound screening using a standardized
Fetal Presentation
Fetal Presentations Ultrasound Images
SOLUTION: Fetal presentation ultrasound
Fetal Presentation
fetal presentation on ultrasound ...

VIDEO

Fetal Ultrasound
FMU Case presentation on Placenta Abruptio -Dr S Marangwanda and Report Writing
On-device fetal ultrasound assessment with TensorFlow Lite
pregnancy life
Baby at 13 weeks
Ultrasound Sonography Report #ultrasound #report #sonography

COMMENTS

Sonography Fetal Assessment, Protocols, and Interpretation
Fetal ultrasonography is an essential element in the evaluation of anomalies and fetal well-being throughout pregnancy. The increasing incidence of morbid obesity, hypertension, and gestational diabetes within the reproductive age group places this high-risk population at increased adverse fetal events such as stillbirth and fetal anomalies. In every trimester, there are specific maternal and ...
Ultrasound determination of fetal lie and presentation
The fetal presentation describes the fetal part that is lowest in the maternal abdomen. In case of labor, it is the lowest fetal part in the birth canal. Many fetal presentations are possible: Cephalic presentation: the fetal head is the lowest fetal part. This is by far the most common presentation at term of pregnancy and in labor.
Fetal Presentation, Position, and Lie (Including Breech Presentation
In face presentation, the baby's neck arches back so that the face presents first rather than the top of the head.. In brow presentation, the neck is moderately arched so that the brow presents first.. Usually, fetuses do not stay in a face or brow presentation. These presentations often change to a vertex (top of the head) presentation before or during labor.
Variation in fetal presentation
breech presentation: fetal rump presenting towards the internal cervical os, this has three main types. frank breech presentation (50-70% of all breech presentation): hips flexed, knees extended (pike position) complete breech presentation (5-10%): hips flexed, knees flexed (cannonball position) footling presentation or incomplete (10-30%): one ...
Abnormal Fetal Lie and Presentation
Fetal presentation is a reference to the part of the fetus that is overlying the maternal pelvic inlet. The most common relationship between fetus and mother is the longitudinal lie, cephalic presentation. ... as seen in funic presentations. Ultrasound examination, in conjunction with color Doppler scan, can help to locate the exact position of ...
Fetal Presentation, Position, and Lie (Including Breech Presentation
Fetal lie: Relation of the fetus to the long axis of the uterus; longitudinal, oblique, or transverse. Normal fetal lie is longitudinal, normal presentation is vertex, and occiput anterior is the most common position. Abnormal fetal lie, presentation, or position may occur with. Fetopelvic disproportion (fetus too large for the pelvic inlet)
Sonography 3rd Trimester and Placenta Assessment, Protocols, and
The use of ultrasound in the third trimester of pregnancy serves a multitude of general and specialized purposes that include but are not limited to the determination of fetal number and presentation, assessment of growth disorders, and characterization of the placenta and amniotic fluid. Thus, the ultrasonographic applications in the third trimester of pregnancy differ from previous ...
The clinical ultrasound report: Guideline for sonographers
Fetal heart and face anatomy cannot be assessed due to unfavourable fetal position. Repeat ultrasound in 1 weeks' time is recommended in order to complete fetal morphology assessment. ... (imaging findings, patient's history, clinical presentation, laboratory findings, past imaging and other sources) in formulating a diagnostic opinion ...
Sonography 2nd Trimester Assessment, Protocols, and Interpretation
Antenatal ultrasonography is widely used in pregnancy to assess fetal growth and anatomy. Although ultrasound screening is now an integral part of routine antenatal care, recommendations for the delivery of obstetric ultrasound vary from country to country.[1][2] The history of sonography in obstetrics dates from the classic 1958 Lancet paper of Ian Donald and his team from Glasgow. Clinical ...
Ultrasound determination of fetal lie and presentation
Cephalic presentation: the fetal head is the lowest fetal part. This is by far the most common presentation at term of pregnancy and in labor. Breech: the fetal buttock or feet are the lowest fetal part. Shoulder: the fetal shoulder is the lowest fetal part. Compound: a combination of more than one fetal structure lies closest to the pelvic inlet.
PDF GUIDELINES
ISUOG has published guidance on the use of Doppler ultrasound at the 11 to 13+6-week fetal ultrasound examination1. When performing Doppler imaging, the displayed thermal index (TI) should be 1.0 and expo-. ≤. sure time should be kept as short as possible, usually no longer than 5-10 min and not exceeding 60 min1.
PDF Fetal Presentation
Ultrasound Report File the Viewpoint ultrasound report in woman's hand held notes. Fetal Presentation - Clinical Guideline v2.0 ... Women who have been referred to Fetal Medicine for assessment of fetal presentation should follow the pattern of care as detailed in the policy and this will be monitored. Lead Lead for Fetal Medicine Tool ...
PDF Stepwise Standardized Approach to The Basic Obstetric 10 Ultrasound
Chapter 10: Stepwise Standardized Approach to the Basic Obstetric Ultrasound Examination in the Second and Third Trimester 188 presence of a fetal head on the ultrasound monitor confirms a cephalic presentation Figure ( 10.4) and the presence of fetal buttocks confirms a breech presentation (Figure 10.5).Note that
Consensus Report on the Detailed Fetal Anatomic Ultrasound Examination
This consensus report was developed by the 76811 Task Force, under the leadership of the American Institute of Ultrasound in Medicine (AIUM) and the Society for Maternal-Fetal Medicine (SMFM). The document was developed with the assistance of and reviewed by the American College of Obstetricians and Gynecologists (ACOG) and has been reviewed ...
PDF The 18
Ultrasound is the main diagnostic tool in the prenatal detection of congenital abnormalities. It allows ... The fetal brain undergoes major developmental changes throughout pregnancy. At 7 weeks of gestation, a sonolucent area is seen in the cephalic pole, presumably representing the fluid-filled rhombencephalic vesicle. ...
Fetal Positions For Birth: Presentation, Types & Function
Possible fetal positions can include: Occiput or cephalic anterior: This is the best fetal position for childbirth. It means the fetus is head down, facing the birth parent's spine (facing backward). Its chin is tucked towards its chest. The fetus will also be slightly off-center, with the back of its head facing the right or left.
PDF Chapter 15 WRITING THE ULTRASOUND REPORT
the ultrasound report and should be included in its top section and easily identified. Patient ... amniotic fluid and the presentation and lie of the fetus. Fetal biometric measurements should ... guidelines for performance of the routine midtrimester fetal ultrasound scan. - Ultrasound Obstet Gynecol 2011:37; 116-126. ...
Second trimester ultrasound scan
Citation, DOI, disclosures and article data. The second trimester scan is a routine ultrasound examination in many countries that is primarily used to assess fetal anatomy and detect the presence of any fetal anomalies. The second trimester extends from 13 weeks and 0 days to 27 weeks and 6 days of gestation although the majority of these ...
How to Read a Pregnancy Ultrasound Report
There are two main types of ultrasound procedures done during pregnancy: Transabdominal scan (TAS): A sonographer will squeeze gel onto your belly and then run the transducer over the surface of your skin to capture the fetal anatomy of your growing baby. Transvaginal scan (TVS): A sonographer will insert a lubricated wand into your vagina to ...
PDF Competency Workbook Ultrasound Examination for Fetal Presentation
When competencies are achieved, the midwife will only be able to perform an ultrasound examination to diagnose fetal presentation. The midwife will NOT be competent to perform any other type of ultrasound exam ination. This policy will apply to singleton pregnancies only. Scope of Practice
Ultrasound Report Form (Obstetrics
Ultrasound EDC (if gestation age is >21 weeks): Comments: +/- 2SD: ... Fetal Number: Fetal Heart Rate: BPM. Fetal Presentation: Fetal Heart Rhythm: Fetal Anatomy. Normal. Not Well Seen. Abnormal. Comments. Head. Ventricles. Cerebellum. Cisterna Magna. Nuchal Fold (20 weeks) Face (including profile & lips): Spine (Normal in two planes) ...
Ultrasound for fetal assessment in early pregnancy
Main results. Routine/revealed ultrasound versus selective ultrasound/concealed: 11 trials including 37,505 women. Ultrasound for fetal assessment in early pregnancy reduces the failure to detect multiple pregnancy by 24 weeks' gestation (risk ratio (RR) 0.07, 95% confidence interval (CI) 0.03 to 0.17; participants = 295; studies = 7), moderate quality of evidence).
PDF ULTRASOUND EXAMINATION IN PREGNANCY
The main objective of a second trimester fetal ultrasound scan is to provide accurate diagnostic information on the presence or absence of fetal anomalies. It is recommended that a second-trimester ultrasound scan be performed between 18 and 22 weeks of gestation. Storage of motion video-clips are recommended for the fetal heart assessment.
Routine ultrasound for fetal assessment before 24 weeks' gestation
Routine second trimester ultrasound may increase detection of major fetal abnormality before 24 weeks (RR 3.45, 95% CI 1.67 to 7.12; 387 participants, two studies; low‐certainty evidence, downgraded due to design limitations and imprecision. Imprecision due to low event rate and sample size) ( Analysis 2.15 ). 2.15.