Breastfeeding reduces postpartum weight retention

Background: Weight gained during pregnancy and not lost postpartum may contribute to obesity in women of childbearing age. Objective: We aimed to determine whether breastfeeding reduces postpartum weight retention (PPWR) in a population among which full breastfeeding is common and breastfeeding duration is long. Design: We selected women from the Danish National Birth Cohort who ever breastfed (> 98%), and we conducted the interviews at 6 (n = 36 030) and 18 (n = 26 846) mo postpartum. We used regression analyses to investigate whether breastfeeding (scored to account for duration and intensity) reduced PPWR at 6 and 18 mo after adjustment for maternal prepregnancy body mass index (BMI) and gestational weight gain (GWG). Results: GWG was positively (P < 0.0001) associated with PPWR at both 6 and 18 mo postpartum. Breastfeeding was negatively associated with PPWR in all women but those in the heaviest category of prepregnancy BMI at 6 (P < 0.0001) and 18 (P < 0.05) mo postpartum. When modeled together with adjustment for possible confounding, these associations were marginally attenuated. We calculated that, if women exclusively breastfed for 6 mo as recommended, PPWR could be eliminated by that time in women with GWG values of approximate to 12 kg, and that the possibility of major weight gain (>= 5 kg) could be reduced in all but the heaviest women. Conclusion: Breastfeeding was associated with lower PPWR in all categories of prepregnancy BMI. These results suggest that, when combined with GWG values of approximate to 12 kg, breastfeeding as recommended could eliminate weight retention by 6 mo postpartum in many women. Am J Clin Nutr 2008; 88: 1543-51.