Different weight gain in women of normal weight before pregnancy: postpartum weight and birth weight.

OBJECTIVE: To identify the effect of different gestational weight gains among women of normal weight before pregnancy on babies' birth weights, and women's weights 18-24 months postpartum.
METHODS: Two groups of women of normal weight before pregnancy (body mass index [BMI] 19.6-25.4 kg/m2) took part in the study (n = 200). They gained either moderate weight (9-15 kg) or high weight (18-24 kg) during pregnancy. From maternity records and telephone interviews, information on age, height, prepregnancy and postpartum weight, gestational weight gain, babies' birth weights, lactation, parity, and smoking habits was collected.
RESULTS: High maternal weight gain during pregnancy resulted in mean birth weight 286 g higher than that of babies of mothers who gained moderate weight. The correlation coefficient between birth weight and gestational weight gain was 0.3 (P < .001). The postpartum weight of women with high weight gain during pregnancy was 2.6+/-0.38 kg (mean +/- standard error of the mean [SEM]) more than before pregnancy but the group of moderate weight gain weighed 0.1+/-0.47 kg less than before pregnancy (P < .001). However, most women in both groups (88.6%) regained normal weight, and prepregnant weight correlated strongly with the weight 18-24 months postpartum (r = 0.79, P < .001). There was not a significant correlation between the duration of lactation and postpartum weight loss (r = 0.04, P > .05).
CONCLUSION: High gestational weight gain among women of normal weight before pregnancy increases birth weight and women's weight postpartum, compared with moderate weight gain. Prepregnant weight is more indicative of postpartum weight, and women reach normal weight again irrespective of gestational weight gain.