Maternal and Perinatal Factors Associated with the Human Milk Microbiome

Abstract

Microbes are present in human milk regardless of the mother's health. The origins of the milk microbiota likely include the mother's skin, infant's mouth, and transfer from the maternal gastrointestinal (GI) tract. Prominent bacterial taxa in human milk are Staphylococcus and Streptococcus, but many other genera are also found including anaerobic Lactobacillus, Bifidobacterium, and Bacteroides. The milk microbiome is highly variable and potentially influenced by geographic location, delivery mode, time postpartum, feeding mode, social networks, environment, maternal diet, and milk composition. Mastitis alters the milk microbiome, and the intake of Lactobacilli has shown potential for mastitis treatment and prevention. Although milk and infant fecal microbiomes are different, their variations appear to be related - suggesting that milk is an important contributor of early GI colonization. Nonetheless, nothing is known regarding whether the milk microbiome influences infant health. Further research and clinical interventions are needed to determine if changes in the microbiomes of human milk and infant formula/food impact health.

Keywords: composition; entero-mammary pathway; geographical setting; human milk; mastitis; milk microbiome; variation.

FIGURE 1

Human milk composition and the human milk microbiome are determined by a complex interplay of biological processes occurring in mother and infant. Besides biological factors such as health and diet of the mother and growth of the infant, the geographical setting, which might include among other factors climate, available economic resources, culture and societal support could influence human milk composition and the microbiome.

FIGURE 2

Considerable knowledge in relation to the human milk microbiome has already been acquired but further research on the origin of the human milk microbiota, the influencing factors, and their association with health outcomes is needed to enable consideration of the human milk microbiome in future recommendations and dietary products. GI, gastrointestinal.