Doppler ultrasound of umbilical and middle cerebral artery in third trimester small-for-gestational age fetuses to decide on timing of delivery for suspected fetal growth restriction: A cohort with nested RCT (DRIGITAT)

Objective: To assess the association of the umbilicocerebral ratio (UCR) with adverse perinatal outcome in late preterm small-for-gestational age (SGA) fetuses and to investigate the effect on perinatal outcomes of immediate delivery. Design: Multicentre cohort study with nested randomised controlled trial (RCT). Setting: Nineteen secondary and tertiary care centres. Population: Singleton SGA pregnancies (estimated fetal weight [EFW] or fetal abdominal circumference [FAC] <10th centile) from 32 to 36⁺⁶ weeks. Methods: Women were classified: (1) RCT-eligible: abnormal UCR twice consecutive and EFW below the 3^rd centile at/or below 35 weeks or below the 10^th centile at 36 weeks; (2) abnormal UCR once or intermittent; (3) never abnormal UCR. Consenting RCT-eligible patients were randomised for immediate delivery from 34 weeks or expectant management until 37 weeks. Main outcome measures: A composite adverse perinatal outcome (CAPO), defined as perinatal death, birth asphyxia or major neonatal morbidity. Results: The cohort consisted of 690 women. The study was halted prematurely for low RCT-inclusion rates (n = 40). In the RCT-eligible group, gestational age at delivery, birthweight and birthweight multiple of the median (MoM) (0.66, 95% confidence interval [CI] 0.59–0.72) were significantly lower and the CAPO (n = 50, 44%, p < 0.05) was more frequent. Among patients randomised for immediate delivery there was a near-significant lower birthweight (p = 0.05) and higher CAPO (p = 0.07). EFW MoM, pre-eclampsia, gestational hypertension and Doppler classification were independently associated with the CAPO (area under the curve 0.71, 95% CI 0.67–0.76). Conclusions: Perinatal risk was effectively identified by low EFW MoM and UCR. Early delivery of SGA fetuses with an abnormal UCR at 34–36 weeks should only be performed in the context of clinical trials.