Assessment of the Cerebroplacental Ratio and Amniotic Fluid Index in Term Appropriate-for-Gestational-Age Pregnancies for Prediction of Adverse Perinatal Outcomes.

backgroundDetermining fetuses at risk of adverse perinatal outcomes at term remains a clinical challenge, particularly among pregnancies that appear low risk and appropriately grown for gestational age (AGA). While the cerebroplacental ratio (CPR) and amniotic fluid index (AFI) are established non-invasive indicators of fetal well-being, their combined predictive ability in low-risk AGA pregnancies is not well defined.

objectiveTo evaluate and compare the predictive value of AFI alone and AFI combined with CPR in forecasting adverse perinatal outcomes among term AGA pregnancies.

methodsThis prospective observational study included 236 term AGA pregnancies, spanning 37 to 40 weeks of gestation. Participants were randomly assigned to two groups: Group 1 (AFI + CPR) and Group 2 (AFI only). Maternal characteristics, intrapartum findings, and neonatal outcomes were recorded. Statistical analyses, including receiver operating characteristic (ROC) curves, were used to assess the predictive performance of AFI and CPR for low Apgar (appearance, pulse, grimace, activity, respiration) scores, neonatal intensive care unit (NICU) admissions, and caesarean delivery.

resultsBaseline maternal and fetal characteristics were comparable between the groups. Normal vaginal delivery was the predominant mode of delivery, with no significant difference in neonatal morbidity or caesarean section rates between groups. ROC analysis demonstrated poor discriminatory ability of both AFI and CPR in predicting low Apgar scores, NICU admissions, or caesarean delivery. However, both parameters exhibited high negative predictive values, indicating utility in ruling out adverse outcomes. The addition of CPR did not significantly improve diagnostic accuracy compared to AFI alone.

conclusionIn low-risk term AGA pregnancies, AFI remains a practical and widely used component of routine fetal surveillance, primarily reflecting its high negative predictive value rather than strong discriminatory capability for adverse outcomes. The inclusion of CPR does not provide a significant incremental benefit in predicting adverse perinatal outcomes, as both parameters demonstrate poor discriminatory performance. These findings support the role of AFI and CPR in excluding adverse outcomes rather than in predicting fetal compromise.