Scanning for serious structural issues in fetuses during the first trimester can result in earlier detection of these issues, reports a new study led by Aris Papageorghiou at the University of Oxford, United Kingdom, published November 25th in the open-access journal PLOS Medicine.
In England, pregnant people typically undergo a basic ultrasound at 12 weeks to assess the gestational age. Whereas an ultrasound at around 20 weeks – during the second trimester – is used to detect serious problems called congenital anomalies, which occur in about 2-3% of pregnancies. Advances in imaging, however, now make it possible to screen for these anomalies even earlier. While first trimester scans are becoming more common in England, currently there is no policy recommending earlier evaluations, and it is unknown whether these screens will result in earlier diagnosis of anomalies.
In the new study, Papageorghiou and his colleagues looked at data from a nationwide survey of first trimester ultrasound protocols across England and the diagnoses of 14 major fetal anomalies from more than 1 million pregnancies occurring between April 2017 and March 2019. They found that hospitals using extensive early ultrasound protocols detected significantly more anomalies before 16 weeks of pregnancy. These hospitals detected about 40% of anomalies early, compared to 28% in hospitals with no protocol for detecting anomalies during an early scan. Some anomalies, like acrania, where the skull does not form, were commonly found early regardless of policy, while others, like heart defects or limb abnormalities, were more likely to be picked up only in hospitals that did perform detailed first trimester scans.
Overall, the nationwide data set revealed significant variations in first-trimester ultrasound practices in England and demonstrated that more detailed early screening protocols are associated with higher early detection rates of fetal anomalies. While current practices vary considerably across England, the study provides evidence that systematic first trimester screening could improve the timeliness of anomaly detection across the population. The researchers conclude that a national policy requiring detailed first trimester ultrasounds could ensure equitable and effective prenatal care for all pregnant people.
Dr Jehan Karim, lead researcher, notes, "With advancing ultrasound technology much earlier detection of serious fetal conditions is now feasible; our guidance must catch up to these developments so families can benefit."
Prof Aris Papageorghiou adds, "A single, focused first-trimester ultrasound scan brings the diagnosis of major fetal conditions forward by weeks; this gives families time to consider and expand clinical options. However, the lack of guidance has led to variation in practice. Our findings are clear: an organized first-trimester scan is the most effective step to improve prenatal detection across the NHS."
In your coverage, please use this URL to provide access to the freely available paper in PLOS Medicine: https://plos.io/4lnLM8W
Citation: Karim JN, Broughan JM, Aldridge N, Pandya P, McHugh A, Papageorghiou AT, et al. (2025) Impact of first-trimester ultrasound on early detection of major fetal anomalies: Nationwide population-based study of over 1 million pregnancies. PLoS Med 22(11): e1004709. https://doi.org/10.1371/journal.pmed.1004709
Author countries: United Kingdom
Funding: see manuscript
