Objective: Numerous studies in the U.S. and elsewhere have reported an increased risk of gestational diabetes mellitus (GDM) among women who are overweight or obese compared with lean or normal-weight women. Despite the number and overall consistency of studies reporting a higher risk of GDM with increasing weight or BMI, the magnitude of the association remains uncertain. This meta-analysis was conducted to better estimate this risk and to explore differences across studies.
Research design and methods: We identified studies from three sources: 1) a PubMed search of relevant articles published between January 1980 and January 2006, 2) reference lists of publications selected from the PubMed search, and 3) reference lists of review articles on obesity and maternal outcomes published between January 2000 and January 2006. We used a Bayesian model to perform the meta-analysis and meta-regression. We included cohort-designed studies that reported obesity measures reflecting pregnancy body mass, that had a normal-weight comparison group, and that presented data allowing a quantitative measurement of risk.
Results: Twenty studies were included in the meta-analysis. The unadjusted ORs of developing GDM were 2.14 (95% CI 1.82-2.53), 3.56 (3.05-4.21), and 8.56 (5.07-16.04) among overweight, obese, and severely obese compared with normal-weight pregnant women, respectively. The meta-regression analysis found no evidence that these estimates were affected by selected study characteristics (publication date, study location, parity, type of data collection [retrospective vs. prospective], and prevalence of GDM among normal-weight women).
Conclusions: Our findings indicate that high maternal weight is associated with a substantially higher risk of GDM.