Cerebroplacental Ratio at Term as a Predictor of Neonatal Adverse Outcomes in Gestational Diabetes Mellitus Pregnancies

Abstract

Background & Objective: The Cerebroplacental Ratio (CPR), calculated from the pulsatility indices of the fetal middle cerebral and umbilical arteries, is a Doppler marker of fetal health. Its prognostic value in Gestational Diabetes Mellitus (GDM) remains uncertain. The present study was conducted with aim to evaluate the diagnostic accuracy of CPR at term in predicting adverse neonatal outcomes in GDM pregnancies. Materials & Methods: This cross-sectional study was conducted on 260 women with GDM at ≥37 weeks, recruited at Kasr Al-Ainy Hospital, Cairo University, from October 2022 to June 2024. Participants were divided equally into insulin-treated and metformin-treated groups. Doppler ultrasound was performed at 37 and 39 weeks to calculate CPR, with values below the 10th percentile considered abnormal. Adverse neonatal outcomes included hypoglycemia, cord pH <7.25, Apgar score <7 at 1 or 5 minutes, or NICU admission >24 hours. Diagnostic performance of CPR was assessed using sensitivity, specificity, predictive values, and accuracy. Results: Maternal and neonatal characteristics were comparable between the two groups. NICU admission occurred in 12.3% of the insulin group and 7.7% of the metformin group (P=0.214). CPR showed low sensitivity (13.8%) but high specificity (96.1%) and overall accuracy of 86.9% for predicting neonatal adverse outcomes. No significant difference was found between the two groups in terms of CPR values. Conclusion: In GDM pregnancies, CPR at term demonstrated high specificity but poor sensitivity for predicting neonatal adverse outcomes. It should not be used alone as a screening tool but interpreted alongside clinical and biochemical indicators.