Body Mass Index and Adverse Neonatal Outcomes in Women Undergoing Elective Cesarean: A Nationwide Cohort Study [25O

Abstract

INTRODUCTION: To examine the association between pre-pregnancy body mass index (BMI) and neonatal outcomes among women who underwent elective cesarean section (CS). METHODS: We conducted a retrospective cohort study using data from the Center for Disease Control and Prevention (CDC) for all reported births by elective CS in 2011-2013. Women's pre-pregnancy BMI was categorized as underweight (“less than”18.5), normal (18.5-24.5), overweight (25-29.9), obese (30-39.9) and morbidly obese (“equal or above”40). Odds ratio (OR) and 95% confidence intervals (CIs) adjusted for baseline characteristics were calculated to estimate the neonatal risks in relation to pre-pregnancy BMI, using normal BMI as our reference. RESULTS: Our cohort was composed of 737,548 women with available BMI data, of whom 2.8% were underweight, 38.8% had normal BMI, 26.3% were considered overweight, 25.0% obese, and 7.2% morbidly obese. Infant mortality rates were of 4.2/1000 births for normal weight women, and 5.5/1000 births among the morbidly obese group (OR 1.43; 95% CI 1.25-1.64). A dose-dependent relationship between maternal pre-pregnancy BMI and assisted ventilation was seen. Furthermore, infants born to morbidly obese women were at significantly increased risk for assisted ventilation over 6 hours (OR 1.24; 95% CI 1.15-1.35) and admission to intensive care units (OR 1.17; 95% CI 1.13-1.21). Risk for adverse outcomes is higher with elective CS at earlier gestational age, and this effect is intensified with abnormally elevated maternal BMI. CONCLUSION: Increasing maternal pre-pregnancy BMI in women undergoing elective CS was found to be associated with progressively higher risks of adverse neonatal outcomes and mortality.