Effects of breastfeeding on postpartum weight loss among U.S. women

Objective: The aim of this study is to evaluate the effects of breastfeeding on maternal weight loss in the 12. months postpartum among U.S. women. Methods: Using data from a national cohort of U.S. women conducted in 2005-2007 (N= 2102), we employed propensity scores to match women who breastfed exclusively and non-exclusive for at least three months to comparison women who had not breastfed or breastfed for less than three months. Outcomes included postpartum weight loss at 3, 6, 9, and 12. months postpartum; and the probability of returning to pre-pregnancy body mass index (BMI) category and the probability of returning to pre-pregnancy weight. Results: Compared to women who did not breastfeed or breastfed non-exclusively, exclusive breastfeeding for at least 3. months resulted in 3.2 pound (95% CI: 1.4,4.7) greater weight loss at 12. months postpartum, a 6.0-percentage-point increase (95% CI: 2.3,9.7) in the probability of returning to the same or lower BMI category postpartum; and a 6.1-percentage-point increase (95% CI: 1.0,11.3) in the probability of returning to pre-pregnancy weight or lower postpartum. Non-exclusive breastfeeding did not significantly affect any outcomes. Conclusion: Our study provides evidence that exclusive breastfeeding for at least three months has a small effect on postpartum weight loss among U.S. women.