Pre-pregnancy weight and excess weight gain are risk factors for macrosomia in women with gestational diabetes

Objective:to determine whether women with gestational diabetes mellitus (gdm) whose weight gain exceeded the 2009 institute of medicine (iom) recommendations were more likely to have macrosomia.study design:retrospective cohort study of the association of weight gain in women with class a1 gdm, with term (⩾37 weeks) singleton liveborns and macrosomia (birthweight ⩾4000 g). multivariate logistic regression models were used to adjust for covariates and test for interactions.result:of 1502 women studied, pre-pregnancy body mass index (bmi) categories were: normal (39.6%), overweight (28.5%) and obese (31.9%). the mean (±standard deviation ) weight gain (lbs) for these groups was: 27.6±10.9, 24.2±13.0 and 18.8±16.3 (p<0.0001), whereas the occurrence of macrosomia was 7.4, 11.4 and 19.0%, respectively. women with an obese bmi were twice as likely to have a macrosomic infant compared with women in the normal bmi group (odds ratio, or 2.0; 95% ci 1.4–3.0; p=0.0005). independently, women who exceeded the iom guidelines were three times more likely to have a macrosomic infant (or 3.0, 95% ci 2.2–4.2, p<0.0001).conclusion:maternal pre-pregnancy weight and weight gain during pregnancy appear to be significant and independent risk factors for macrosomia in women with gdm.