Prepregnancy Body Mass Index and Offspring Birth Weight in Women with Type 1 and Type 2 Diabetes

Abstract

Objective: To evaluate offspring birth weight in relation to prepregnancy body mass index in women with pregestational diabetes. Methods: A cohort study of 260 consecutive women with type 1 or type 2 diabetes, included January 2012 to May 2014, and classified as normal weight (prepregnancy body mass index <24.9 kg/m2), overweight (25.0-29.9) or obese (≥30.0). Results: Among 155 women with type 1 diabetes, 55% were normal weight, 27% overweight and 18% obese. Corresponding figures among 105 women with type 2 diabetes were 15%, 22% and 63%. HbA1c in early and late pregnancy and gestational weight gain were comparable across the body mass index categories in both diabetes types. Offspring birth weight across the body mass index categories was 3,514 ±471 vs. 3,534 ±483 vs. 3,483 ±499 g (mean ±SD) (P=0.85) for type 1 diabetes and 3,113 ±767 vs. 3,221 ±567 vs. 3,296 ±839 g (P=0.39) for type 2 diabetes. There were no associations between prepregnancy body mass index and offspring birth weight or birth weight SD-score after adjustment for HbA1c, excessive gestational weight gain, parity, ethnicity, smoking and diabetes type. Women with type 1 diabetes had higher gestational weight gain (15.1 ±6 vs. 11.9 ±7 kg, P <0.001), offspring birth weight (3,514 ±476 vs. 3,251 ±772 g, P <0.001) and birth weight SD-score (1.04±1.3 vs. 0.43±1.7, P <0.001) compared to type 2 diabetes while HbA1c was comparable. Conclusion: In women with pregestational diabetes, offspring birth weight was not associated with prepregnancy body mass index. Gestational weight gain and offspring birth weight were higher in women with type 1 compared to type 2 diabetes.