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

Abstract

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.