Impact of Maternal Body Mass Index on Intrapartum and Neonatal Outcomes in Brisbane, Australia, 2007 to 2013

Abstract

Background: The aim of this study was to evaluate the influence of maternal body mass index on intrapartum and neonatal outcomes at one of the largest maternity hospitals in Australia. Methods: A retrospective cross-sectional study of 55,352 term singleton deliveries at the Mater Mothers’ Hospital in Brisbane, Australia, was conducted. The study cohort was stratified into six groups based on the World Health Organization's body mass index classification. The normal body mass index category was the reference group for all comparisons. Multivariate logistic regression was used to examine the effect of maternal body mass index, adjusted for maternal age, ethnicity, parity, and preexisting conditions (e.g., diabetes mellitus and hypertension), on selected intrapartum and neonatal outcomes. Results: Women in the overweight and Obese I, II, and III categories were more likely to have chronic or gestational hypertension/preeclampsia, and preexisting or gestational diabetes mellitus. They also had an increased risk for induction of labor, elective and emergency cesarean, and postpartum hemorrhage. Underweight women were less likely to require induction of labor and emergency cesarean. Infants born to women with increased body mass index were more likely to require neonatal resuscitation, neonatal intensive care unit admission, and have lower Apgar scores at 5 minutes. Conclusion: There is an increased risk of adverse intrapartum and neonatal outcomes for women who are overweight and obese, with the risks increasing with rising body mass index. Appropriately targeted weight management strategies and health education may yield improved maternal and perinatal outcomes if effectively implemented before pregnancy. These may particularly be of benefit in the teenage cohort that has yet to embark on pregnancy.