The impact of a universal late third-trimester scan for fetal growth restriction on perinatal outcomes in term singleton births: A prospective cohort study

Objective: To investigate perinatal mortality, morbidity and obstetric intervention following the introduction of a universal late third-trimester ultrasound scan for growth restriction. Design: Prospective cohort study. Setting: Oxfordshire (OUH), UK. Population: Women with a non-anomalous singleton pregnancy undergoing pregnancy care and term delivery at OUH with an estimated due date (EDD) of birth between 1 January 2014 and 30 September 2019. Methods: Universal ultrasound for fetal growth restriction between 35+0 and 36+6 weeks was introduced in 2016. The outcomes of the next 18 631 eligible term pregnancies were compared, adjusting for covariates and time, with the previous 18 636 who had clinically indicated ultrasounds only. ‘Screen-positives’ for growth restriction were managed according to a pre-determined protocol which included non-intervention for some small-for-gestational-age babies. Main Outcome Measures: Extended perinatal mortality, a composite of mortality or encephalopathy Grade II–III, and expedited birth. Other outcomes included composite adverse outcomes used elsewhere, detection of low birthweight and birth from 37+0 to 38+6 weeks. Results: Extended perinatal deaths decreased 27% and severe morbidity decreased 33% but neither change was statistically significant (adjusted odd ratio [aOR] 0.53, 95% confidence interval [C1] 00.18–1.56 and aOR 0.71, 95% CI 0.31–1.63). Expedited births changed from 35.2% to 37.7% (aOR 0.99, 95% CI 0.92–1.06). Birthweight (<10th centile) detection using fetal biometry alone was 31.4% and rose to 40.5% if all abnormal scan parameters were used. Conclusion: Improvements in mortality and severe morbidity subsequent to introducing a universal ultrasound for growth restriction are encouraging but remain unclear. Little change in intervention is possible. The antenatal detection of low birthweight remains poor but improves where markers of growth restriction are used.