Glycemic Level Modifies the Relationship between Maternal Gestational Weight Gain and Neonatal Birth Weight in Type 2 Diabetes Mellitus-Complicated Pregnancies

OBJECTIVE To examine whether glycemic level modifies the association between gestational weight gain (GWG) and pregnant outcomes in type 2 diabetes mellitus-complicated pregnancies. RESEARCH DESIGN AND METHODS In this multicenter retrospective study, 1,642 pregnant women with diabetes were stratified by third-trimester glycemic control. Associations between excessive GWG (eGWG) and pregnant outcomes were analyzed by group. RESULTS Although birth weight and odds of macrosomia and cesarean delivery were higher for all females with eGWG relative to those with adequate GWG, the effect estimates for birth weight and macrosomia were significantly higher with suboptimal glycemic control compared with optimal control (birth weight increase: 361.04 vs. 126.07 g, respectively, P = 0.007; adjusted odds ratio for macrosomia: 4.26 vs. 2.73, P = 0.002; cesarean delivery: 1.86 vs. 1.52, P = 0.738). CONCLUSIONS Overly stringent weight control should be treated with caution if optimal glycemic control is not achieved.