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 .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.