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

## TL;DR

This study examines whether combining two fetal monitoring measures improves prediction of poor outcomes in low-risk pregnancies, finding limited benefit.

## Contribution

The study evaluates the combined use of AFI and CPR for predicting adverse outcomes in term AGA pregnancies, a scenario not well studied.

## Key findings

- AFI and CPR showed high negative predictive values but poor discriminatory ability for adverse outcomes.
- Adding CPR to AFI did not significantly improve diagnostic accuracy in predicting adverse perinatal outcomes.
- Both parameters are more useful for ruling out adverse outcomes than predicting them.

## Abstract

Background: Determining 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.

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

Methods: This 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.

Results: Baseline 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.

Conclusion: In 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.