Prevalence of Abnormal Cerebroplacental Ratio in Uncomplicated Full-term Pregnancy and Correlation with Adverse Perinatal Outcomes

Objective: To investigate the prevalence of abnormal cerebroplacental ratio (CPR) and predicting values for adverse perinatal outcomes in uncomplicated full-term pregnancies. Materials and Methods: This prospective cross-sectional study was conducted at Bhumibol Adulyadej Hospital, Royal Thai Air Force, Thailand between July and December 2023. The study population comprised pregnant women between the ages 18 and 45 presenting uncomplicated full-term pregnancies. Transabdominal ultrasonography in Doppler color mode was performed on all participants. Umbilical artery pulsatility index (UAPI) and middle cerebral artery pulsatility index (MCAPI) were both measured. CPR was calculated by MCAPI divided by UAPI. A CPR value was considered low if it was less than 1.03. Obstetric and perinatal outcomes were recorded including route of delivery, gestational age (GA) at delivery, obstetric complications, Apgar score, neonatal birth weight, neonatal intensive care unit (NICU) admission, and fetal non-reassuring tracing (FNR). Results: A total of 250 pregnant women were recruited. The mean maternal age and GA was 27.7 years, 39.6 weeks, respectively. Low CPR prevalence was recorded at 16.4 percent. There were 41 and 209 cases in low (<1.03) and normal (≥1.03) CPR groups, respectively. UAPI and MCAPI of the normal/low CPR group were 0.8/1.3 and 1.1/0.9 with statistical significance. CPR for predicted value of FNR (1.03) gave sensitivity, specificity, PPV, and NPV at 95.5, 91.2, 51.2 and 99.5 percent, respectively. This study presented no adverse perinatal outcomes. Conclusion: Low CPR prevalence was 16.4 percent. Normal CPR values measured within a week before birth was a good indicator of normal perinatal outcomes.