Role of cerebroplacental ratio at 35 to 36 weeks of gestational age in prediction of perinatal out come in asymptomatic pregnant Indian women: a prospective observational study

Abstract

Background: Foetal hypoxia and adverse perinatal outcomes remain significant challenges in obstetrics. The cerebroplacental ratio (CPR)-calculated as middle cerebral artery pulsatility index (MCA PI) divided by umbilical artery pulsatility index (UA-PI)-reflects both placental vascular resistance and brain-sparing foetal adaptation. This study evaluated the predictive value of CPR for adverse perinatal outcomes in low-risk pregnancies. Methods: A prospective cohort study was conducted at Sparsh Hospital, Kannauj, from October 2024 to March 2026, enrolling 100 asymptomatic, low-risk singleton pregnant women at 35 to 36 weeks of gestation. Participants underwent Doppler ultrasonography to measure UA-PI, MCA PI, and CPR. Participants were followed prospectively to evaluate neonatal outcomes, including Apgar scores and Neonatal Intensive Care Unit (NICU) admissions. Spearman’s rho correlation was used for statistical analysis. Results: The mean Apgar score was 9.41±1.61. Mean Doppler values were: UA-PI 1.00±0.334, MCA PI 1.49±0.513, and CPR 1.59±0.601. No statistically significant correlation was observed between Apgar scores and UA PI (rho=-0.058, p=0.568), MCA PI (rho=0.107, p=0.296), or CPR (rho=0.174, p=0.087). However, among 9 patients with CPR <1, 8 babies (88.9%) required NICU admission. Conversely, only 2 of the 91 patients with normal CPR required NICU admission. Conclusions: Although Doppler indices showed no linear correlation with routine Apgar scores, a threshold of CPR <1 at 35-36 weeks was strongly associated with poor perinatal outcomes and NICU admission in low-risk pregnancies. CPR assessment enables early identification of vulnerable foetuses, supporting closer surveillance and timely delivery.