Recently, there has been growing interest in understanding the ways in which lactation affects maternal health. The accompanying article by Palmer et al. (Am J Epidemiol. 2015;181(12):932–939), particularly their finding that prepregnancy obesity modifies the relationship between lactation and postpartum weight gain, makes an important contribution to this field. In this commentary, I discuss these findings within the context of other recent literature which indicates that whether or not a mother breastfeeds her newborn appears to be a powerful predictor of the mother's future risk of developing diabetes, hypertension, and cardiovascular disease, independent of maternal weight or body mass index in later life.