Pre-pregnant body mass index, weight gain and the risk of delivering large babies among non-diabetic mothers.

OBJECTIVE: Pre-pregnancy overweight and excess weight gain during pregnancy have each been associated with an increased risk of delivering large babies. However, previous studies have focused on the separate effects of these two indices of weight in diabetic women. METHOD: This study analyzed both separate and combined effects of pre-pregnant body mass index and weight gain in relation to macrosomia (> or =4000 g) in offspring among 815 non-diabetic women, using data collected from a retrospective study. RESULT: Compared to mothers with normal pre-pregnancy BMI and pregnancy weight gain, risk of macrosomia in offspring was significantly elevated only in overweight women with excess weight gain (adjusted OR=2.6, 95% CI [1.2,5.4]) but not among normal weight mothers with excess gain (adjusted OR=1.1, 95% CI [0.5,2.4]) or overweight mothers with normal or low gain (adjusted OR=1.1, 95% CI [0.4,3.1]). CONCLUSION: Given the complications that are associated with delivering large babies, overweight women may benefit from not gaining excess weight in pregnancy.