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.