A woman’s decision to breastfeed has far-reaching effects, not only for her newborn and infant and her own health but also for the economic and environmental benefits to society. These short- and long-term effects are secondary to the dynamic composition of human milk, which contains anti-infective and anti-inflammatory factors, oligosaccharides that promote a healthy gut microbiome, growth factors, microRNA that are important in modulating epigenetic regulators, and cells such as neutrophils, leukocytes, stem cells, and bacteria—including Bifidobacterium and Lactobacillus (see Chapter 4, Nonnutritive Components in Human Milk). These factors establish the neonatal immune system and gut microbiome, which serve to decrease the incidence and severity of infections and inflammatory reactions. Recent studies emphasize the importance of the “early critical window” in the first year after birth, during which establishing a healthy gut microbiome through breastfeeding can induce long-term effects.¹ 

Given the well-documented short- and long-term medical and neurodevelopmental advantages, breastfeeding should be considered a public health priority. This chapter outlines the risk reductions for acute and chronic illness for baby and mother, as well as the economic effects of breastfeeding.