Evidence continues to accumulate that a woman’s reproductive history affects her long-term risk for metabolic disease. Increasing parity is associated with central adiposity,1
and retained gestational weight gain is associated with adverse outcomes in the next pregnancy2
as well as with long-term obesity risk for the mother.3
Data from several large cohort studies suggest that breast-feeding may reduce a woman’s risk of metabolic complications. Authors have found protective associations between duration of breast-feeding and incidence of type 2 diabetes,4
incidence of myocardial infarction,5
prevalence of the metabolic syndrome,6
and prevalence of hypertension, type 2 diabetes, and hyperlipidemia.7
The physiology of mammalian reproduction provides a biological basis for these associations. During pregnancy, dramatic changes occur in a woman’s metabolism as she accommodates the demands of “metabolizing for two.”8
These changes both support the developing fetus and allow accumulation of energy stores in anticipation of lactation.9
This accumulation is characterized by well-described increases in visceral fat, insulin production, insulin resistance, and circulating lipid levels.10
After birth, we hypothesize that lactation plays a central role in mobilizing these accumulated fat stores and “resetting” maternal metabolism, thereby reducing maternal risk for metabolic disease (). The longer a woman lactates, the more completely she off-loads these accumulated stores. Conversely, when a woman does not lactate, adverse metabolic changes persist for a longer period of time, increasing her disease risk.
Pregnancy is associated with accumulation of fat stores and deleterious changes in glucose and lipid metabolism. We hypothesize that lactation plays a role in “resetting” maternal metabolism after pregnancy.
Both animal and human studies have examined the relation between lactation and maternal metabolism in the postpartum period and beyond. In this article, we explore the role of lactation in resetting maternal metabolism. Evidence assessed includes controlled experiments in animal models, detailed observational studies of maternal metabolism during lactation, and longitudinal cohort studies examining associations between lactation and incident disease.