Abstract
There exists significant evidence of the beneficial effect of breastfeeding on the neonate, but there is comparatively little data on the effect on nursing mothers. It is said that the positive metabolic and vascular effects of breastfeeding are related to an extension or an amelioration of the adaptive mechanisms generated during pregnancy. However, many such vascular and metabolic effects are related to regulation or dysregulation of the immune system. Because of this, interest in some quarters has turned to the study of postpartum immunobiology. This review focuses on the association between breastfeeding and the postpartum immune system. It examines the role of the immune system in breast development and involution, and the molecular biology and potential role of sex and lactation-related hormones important to breastfeeding in immunoregulation. It further describes animal models that may be used to examine relevant underlying mechanisms. It then explores human observational studies that have examined both local and systemic outcomes of immune system related disease in breastfeeding and non-breast-feeding women. It is hoped that this review will further raise interest in the area and generate detailed examination in both animal models and humans.