Increased maternal abdominal subcutaneous fat thickness and body mass index are associated with increased cesarean delivery: A prospective cohort study

Early pregnancy body mass index (BMI) is known to predict adverse pregnancy outcomes but does not account for body fat distribution. This study aimed to prospectively determine if maternal abdominal subcutaneous fat thickness (SCFT) measured by ultrasound at the fetal morphology scan is a better predictor of mode of delivery and other pregnancy outcomes, than BMI. This was a prospective cohort study of women delivering singleton neonates at a tertiary public hospital. Women were included if they had appropriate images at the routine fetal anomaly ultrasound scan and who delivered in the facility. The primary outcome was mode of delivery categorised as cesarean section or vaginal delivery. The relationship between maternal SCFT and BMI was described using the Pearson correlation coefficient. The association of maternal abdominal SCFT BMI at booking-in with pregnancy outcomes were compared using univariate linear and logistic regression. SCFT and BMI were obtained for 997 women. The median (interquartile range) SCFT was 15.3 mm (12.8-19.6) and median (interquartile range) BMI 24.3 kg/m (21.7-28.3). Maternal abdominal SCFT and BMI were highly correlated (R =0.55). Both were significantly associated with cesarean delivery: SCFT per 5 mm, OR 1.32 (95% CI: 1.18 - 1.48); BMI per 5 kg/m OR 1.29 (95% CI: 1.15 - 1.44). Maternal abdominal SCFT and BMI were both significantly associated with cesarean delivery and other outcomes. More research is needed to define the strengths of maternal SCFT in predicting pregnancy outcomes.