Gestational weight gain and gestational diabetes mellitus: perinatal outcomes.

OBJECTIVE: To examine the association between gestational weight gain and perinatal outcome in women with gestational diabetes mellitus (GDM). METHODS: This is a retrospective cohort study of women with nonanomalous singleton pregnancies with GDM enrolled in the Sweet Success California Diabetes and Pregnancy Program between 2001 and 2004. Gestational weight gain, calculated from prepregnancy weight and weight at last prenatal Sweet Success visit, was subgrouped into below, within, and above the Institute of Medicine (IOM) weight-gain guidelines. Perinatal outcomes were examined using Χ 2 test and multivariable regression analysis with 15-35-lb weight gain as the reference group. RESULTS: There were 31,074 women meeting study criteria. Compared with women with gestational weight gain within the IOM guidelines, women who gained above the guidelines had higher odds of having large for gestational age neonates (adjusted odds ratio [aOR] 1.72, 95% confidence interval [Cl] 1.53-1.93, number needed to harm 10), preterm delivery (aOR 1.30, 95% Cl 1.14-1.48, number needed to harm 32), and primary cesarean delivery (aOR 1.52, 95% Cl 1.26-1.83, number needed to harm 10). Women who gained below the guidelines had higher odds of having small for gestational age neonates (aOR 1.39, 95% Cl 1.01-1.90) and maintaining diet-controlled GDM (aOR 1.47, 95% Cl 1.34-1.63) and lower odds of having large for gestational age neonates (aOR 0.60, 95% Cl 0.52-0.67). CONCLUSION: Women diagnosed with GDM who had gestational weight gain above the IOM guidelines have higher risk of undesirable outcomes, including preterm delivery, having macrosomic neonates, and cesarean delivery. Women who gained below guidelines are more likely to remain on diet control but have small for gestational age neonates.