Duration of Lactation and Maternal Metabolism at 3 Years Postpartum

OBJECTIVE: Lactation has been associated with reduced risk of type 2 diabetes and the metabolic syndrome in mothers. We examined the relation between breastfeeding duration and metabolic markers at 3 years postpartum. METHODS: We used linear regression to relate duration of lactation to maternal glucose and lipid metabolism, inflammatory markers, and anthropometry at 3 years postpartum among 570 participants with 3-year blood samples (175 fasting) in Project Viva, a cohort study of mothers and children. RESULTS: Among the participants, 88% had initiated breastfeeding, and 26% had breastfed >or=12 months. In multivariate analyses, we observed no consistent trends relating duration of lactation to maternal metabolism at 3 years postpartum. Women who exclusively breastfed for >6 months had lower postpartum weight retention at 3 years than women with shorter durations of exclusive breastfeeding (multivariate adjusted predicted mean -0.5, -3.6-2.6 kg vs. 4.8, 2.0-7.6 kg for those who never exclusively breastfed, partial F p = 0.03). CONCLUSIONS: In this prospective cohort study, we did not observe a dose-response relationship between duration of lactation and metabolic risk at 3 years postpartum.