Sex-Specific Doppler Patterns of the Umbilical Artery, Middle Cerebral Artery, and Descending Abdominal Aorta in an African Pregnancy Cohort

Introduction: Fetal sex is increasingly recognized as a biological variable that may influence placental development, fetal circulation, and pregnancy outcomes. However, sex-specific fetal Doppler data are limited in African populations. This study assessed whether Doppler indices of the umbilical artery (UA), middle cerebral artery (MCA), and descending abdominal aorta (DA) differ by fetal sex in a Ghanaian pregnancy cohort. Methods: A prospective cross-sectional study was conducted among 239 low-risk singleton pregnancies attending antenatal care at the AngloGold Ashanti Health Foundation in Ghana. Fetal biometry, estimated fetal weight, fetal heart rate, and Doppler velocimetry of the UA, MCA, and DA were obtained using standardized ultrasound protocols. Fetal sex was determined antenatally and confirmed after delivery. Doppler indices were compared between male and female fetuses overall and after stratification by gestational age (≤25, 26-35, and >35 weeks) using independent-samples t-tests or Mann-Whitney U tests, with statistical significance set at p < 0.05. Results: Male fetuses accounted for 53.6% (128/239) of the cohort, whereas female fetuses accounted for 46.4% (111/239). When all gestational ages were pooled, UA, MCA, and DA Doppler indices did not differ significantly by fetal sex. However, sex-specific patterns were observed at ≤25 weeks of gestation. Female fetuses had higher UA pulsatility index (p = 0.023), resistive index (p = 0.037), and systolic/diastolic ratio (p = 0.023), suggesting higher early fetoplacental impedance. In contrast, male fetuses had higher DA pulsatility index (p = 0.048) and resistive index (p = 0.015), suggesting higher early systemic vascular resistance. Between 26 and 35 weeks and after 35 weeks, most Doppler differences were not statistically significant. Male fetuses had higher fetal heart rates after 35 weeks (144 ± 8.67 vs 140 ± 8.92 bpm, p = 0.035). Conclusions: In this Ghanaian cohort, fetal sex was not associated with significant overall differences in UA, MCA, or DA Doppler indices, but gestational age-specific differences were observed in early pregnancy. Female fetuses showed higher early UA impedance, whereas male fetuses showed higher early DA impedance and higher fetal heart rates in late gestation. These findings support consideration of fetal sex as a biological variable in Doppler-based fetal surveillance and highlight the need for population-specific reference data in African cohorts.