Amniotic‐umbilical‐to‐cerebral ratio, a Doppler index for estimating adverse perinatal outcomes in fetal growth restriction

OBJECTIVE: To evaluate amniotic fluid volume with Doppler parameters and its association with composite adverse perinatal outcomes (CAPOs) in fetal growth restriction (FGR). MATERIALS AND METHODS: This study was conducted prospectively in a tertiary referral center between 2023 and 2024 on pregnant women diagnosed with early- and late-onset FGR. Fetal ultrasonographic measurements, including deepest vertical pocket (DVP) for amniotic fluid, and Doppler parameters including uterine artery (UtA) systolic/diastolic (S/D) and pulsatility index (PI), middle cerebral artery (MCA) S/D and PI, and umbilical artery (UA) S/D and PI, were conducted following fetal biometry. The cerebroplacental ratio (CPR), cerebral ratio, cerebro-placental-uterine ratio (CPUR), and amniotic-umbilical-to-cerebral ratio (AUCR) were all calculated. Pregnant women diagnosed with FGR were planned to give birth after 37 weeks' gestation, unless a pregnancy complication requiring earlier delivery occurred. We assessed perinatal outcomes subsequent to delivery, with CAPOs defined as the presence of at least one adverse outcome: 5th minute APGAR score <7, respiratory distress syndrome (RDS), umbilical cord blood pH <7.2, and neonatal intensive care unit (NICU) admission. RESULTS: The study included 132 participants, divided into early- (n = 32) and late-onset FGR (n = 100) groups. AUCR was significantly lower in fetuses with late-onset FGR who experienced CAPOs. Multivariate analysis showed gestational age at birth and birth weight were significant predictors of CAPOs in early-onset FGR, while gestational age, birth weight, and AUCR were significant predictors in late-onset FGR. CPR, UCR, and CPUR did not show significance in predicting CAPOs in both early- and late-onset FGR on multivariate analysis. CONCLUSIONS: AUCR is a potential reliable marker for predicting adverse perinatal outcomes in late-onset FGR.