Screening for adverse perinatal outcomes: uterine artery Doppler, cerebroplacental ratio and estimated fetal weight in low-risk women at term.

Objective: To stratify apparently low-risk pregnant women into those who are at risk of adverse perinatal outcomes. Appropriate stratification would allow targeted prenatal and intrapartum management.

Methods: This prospective, observational study included normotensive women with appropriately grown, non-anomalous, singleton pregnancies. Participants underwent fortnightly ultrasounds from 36 weeks' gestation and intrapartum and neonatal outcomes were recorded. The association between uterine artery pulsatility index (UtA-PI), the cerebroplacental ratio (CPR) and estimated fetal weight (EFW) were explored along with their screening performance for CS-IFC and CNM.

Results: The final cohort included 429 women. As continuous variables, UtA-PI and the CPR were not correlated (rho = -0.05, p = .33). UtA-PI >95 centile and the CPR <10 centile were predictive of CS-IFC and CNM, with the highest sensitivity achieved by their combination (33.3%, 95% CI 11.6-55.1) for a false positive rate (FPR) of 15.8% (12.3-19.3). For CNM, the highest sensitivity (28.4%, 95% CI 18.6-38.2) and corresponding FPR (17.0%, 95% CI 13.0-20.9) was achieved by combining UtA-PI 95 centile, the CPR 10 centile and EFW 10 centile. EFW was the weakest of the three predictors.

Conclusion: In this population, UtA-PI 95 centile and the CPR 10 centile have modest screening performance for CS-IFC and CNM.