Weight Loss Instead of Weight Gain within the Guidelines in Obese Women during Pregnancy: A Systematic Review and Meta-Analyses of Maternal and Infant Outcomes

BACKGROUND: Controversy exists about how much, if any, weight obese pregnant women should gain. While the revised Institute of Medicine guidelines on gestational weight gain (GWG) in 2009 recommended a weight gain of 5–9 kg for obese pregnant women, many studies suggested even gestational weight loss (GWL) for obese women. OBJECTIVES: A systematic review was conducted to summarize pregnancy outcomes in obese women with GWL compared to GWG within the 2009 Institute of Medicine guidelines (5–9 kg). DESIGN: Five databases were searched from 1 January 2009 to 31 July 2014. The Cochrane Handbook for Systematic Reviews of Interventions and the PRISMA Statement were followed. A modified version of the Newcastle-Ottawa scale was used to assess individual study quality. Small for gestational age (SGA), large for gestational age (LGA) and preterm birth were our primary outcomes. RESULTS: Six cohort studies were included, none of which assessed preterm birth. Compared to GWG within the guidelines, women with GWL had higher odds of SGA <10(th) percentile (adjusted odds ratio [AOR] 1.76; 95% confidence interval [CI] 1.45–2.14) and SGA <3(rd) percentile (AOR 1.62; 95% CI 1.19–2.20) but lower odds of LGA >90(th) percentile (AOR 0.57; 95% CI 0.52–0.62). There was a trend towards a graded relationship between SGA <10(th) percentile and each of three obesity classes (I: AOR 1.73; 95% CI 1.53–1.97; II: AOR 1.63; 95% CI 1.44–1.85 and III: AOR 1.39; 95% CI 1.17–1.66, respectively). CONCLUSION: Despite decreased odds of LGA, increased odds of SGA and a lack of information on preterm birth indicate that GWL should not be advocated in general for obese women.