High pregnancy weight gain and risk of excessive fetal growth

Objective The purpose of this study was too assess whether prepregnancy body mass index (BMI) modifies the relationship between pregnancy weight gain and large for gestational age (LGA; > 90% of birthweight for gestational age) or macrosomia (≥ 4500 g). Study Design This was a population-based cohort study of 104,980 singleton, term births from 2000-2005. Results Prepregnancy BMI modified the relationship between weight gain and LGA. Lean women had higher odds of LGA than overweight or obese women for weight gain ≥ 36 lb. For macrosomia, prepregnancy BMI did not modify the association. Compared with women who gained 15-25 lb, the aOR for a gain of 26-35 lb was 1.5 (95% confidence interval [CI], 1.2-1.9), for a gain of 36-45 lb was 2.1 (95% CI, 1.7-2.7), and for a gain of ≥ 46 lb was 3.9 (95% CI, 3.0-5.0). Conclusion Current pregnancy weight gain recommendations include weight gain ranges that are associated with increased risk of LGA and macrosomia.