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

Abstract

Introduction: 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 determine prospectively whether maternal abdominal subcutaneous fat thickness (SCFT) measured by ultrasound at the fetal morphology scan is a better predictor than BMI of mode of delivery and other pregnancy outcomes.

Material and methods: 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 delivered in the facility. The primary outcome was mode of delivery categorized as cesarean section or vaginal delivery. The relation between maternal SCFT and BMI was described using the Pearson correlation coefficient. The association of maternal abdominal SCFT BMI at booking-in was compared with pregnancy outcomes using univariate linear and logistic regression.

Results: 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/m² (21.7-28.3). Maternal abdominal SCFT and BMI were highly correlated (R² = 0.55). Both were significantly associated with cesarean delivery: SCFT per 5 mm (odds ratio [OR] 1.32, 95% confidence interval (CI) 1.18-1.48; BMI per 5 kg/m² OR 1.29, 95% CI 1.15-1.44.

Conclusions: 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.

Keywords: body mass index; obesity; pregnancy; subcutaneous fat thickness.