Does the Amount of Gestational Weight Gain Modify the Risk of Adverse Maternal and Neonatal Outcomes for Obese Women?

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Background: Obesity during pregnancy is growing in prevalence. There has been a significant linear increase in the prevalence of obesity in American women from 35% (95% CI: 32 – 38) in 2005 to 40.5% (95% CI: 37.6 – 43.4) in 2014 (1). The increase in prevalence of obesity (body mass index (BMI) ≥ 30 kg/m2) is also seen in women of reproductive age (2). Previous studies suggested that the Institute of Medicine (IOM) gestational weight gain (GWG) guidelines needed modification by obesity severity. Objectives: The present study investigated whether the IOM guidelines for obese women needed modification for obesity severity by determining the risk of maternal, obstetric, and neonatal outcomes for class I, II and III obese pregnant women who either: lost weight during pregnancy, gained below the IOM guidelines, or gained above the IOM guidelines, compared to women who gained within the IOM guidelines (11-20 lbs). Methods: A cross-sectional study using 2014 U.S. birth certificate data (N=646,642). Chi-square tests examined associations between GWG categories and adverse outcomes. Log-binomial regression models were built to examine relative risks of adverse maternal, obstetric, and neonatal outcomes following adjustment for maternal age, education, marital status, race, insurance status, and parity. Results: The observed pattern of association was the same between all 3 obese classes indicating evidence for a single GWG recommendation for all 3 classes of obesity. Obese women who lost weight during pregnancy or gained below the IOM recommendations were at a significantly decreased risk for caesarean delivery (RR, 95% CI class I: 0.92, 0.90-0.94; II: 0.91, 0.89-0.93; III: 0.92, 0.90-0.93) and large-for-gestational age (LGA) births (class I: 0.80, 0.77-0.83; II: 0.76, 0.73-0.78; III: 0.73, 0.70-0.75) but had a significantly increased risk of small-for-gestational age (SGA) births (class I: 1.34, 1.26-1.43; II: 1.381.28-1.49; III: 1.35, 1.24-1.46) compared to women who had GWG within IOM guidelines. Obese women who gained above IOM guidelines were at an increased risk for caesarean delivery and LGA births but are at a decreased risk for SGA births. Conclusion: A single GWG recommendation for all obese women is possible, but 2009 IOM guidelines may need to be updated as current recommendations may be too high.
Obstetrics and Gynecology
Salmon, C. N. (2017). Does the Amount of Gestational Weight Gain Modify the Risk of Adverse Maternal and Neonatal Outcomes for Obese Women? (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from doi:10.11575/PRISM/25732