OP01.09: Ultrasound predictors of abnormal severe neonatal outcomes in late fetal growth restriction

There is no published clinical trial demonstrating any benefit in timing delivery at term for late fetal growth restriction (FGR). The aim of this study was to determine the predicting performance of ultrasound parameters for severe abnormal neonatal outcomes in cases of late FGR. This was a prospective study of women with a non-anomalous singleton pregnancy recruited from 32 weeks, at University College London Hospital, UK, between 2018 and 2022. Inclusion criteria comprised any of the following: estimated fetal weight (EFW) ≤ 10th centile (c.), abdominal circumference (AC) decrease ≥50th c. compared to a previous scan, umbilical artery (UmbA) Doppler pulsatility index (PI) >95th c. or cerebroplacental ratio (CPR) < 5th c. High-risk cases were delivered at 37-38 weeks if EFW < 10th c. plus any of the following: EFW < 3rd c. or AC >50 c. drop, or UmbA PI >95th c. or CPR < 5th c. Otherwise, late FGR was considered low-risk and managed conservatively until 40-41 weeks. Severe abnormal neonatal outcome was defined as a composite of any of the following: stillbirth, neonatal or infant death, advanced resuscitation, 5 min APGAR < 7, UmbA pH < 7, sepsis, cerebral, respiratory and circulatory morbidity. 1166 women were recruited and severe abnormal neonatal outcome rate was 12.9% (51/394) and 4.9% (38/772) in the high-risk and low-risk groups, respectively; OR 2.63 (95% CI 1.76, 3.93; p < 0.001). Univariate analysis demonstrated that EFW between 3rd and 10th c. plus CPR< 5th c. and UmbA PI >95th c. were associated with severe abnormal outcomes: OR 2.6 (95%CI 1.31, 5.17; p = 0.006) and OR 4.78 (95%CI 2.38, 9.60; p < 0.001) respectively. However, multivariate analysis showed only UmbA PI >95th c. remained significant, with adjusted OR 2.87 (95%CI 1.208, 6.8; p = 0.017). Multivariate analysis identified UmbA PI >95th c. as the most predictive parameter for severe abnormal neonatal outcome in late FGR cases managed prospectively using a multiparameter strategy.