Composition and Variation of the Human Milk Microbiome is Influenced by Maternal and Early Life Factors

Abstract

Breastmilk contains a complex community of bacteria that may help seed the infant gut microbiota. The composition and determinants of milk microbiota are poorly understood. Among 393 mother-infant dyads from the CHILD cohort, we found that milk microbiota at 3–4 months postpartum was dominated by inversely correlated Proteobacteria and Firmicutes, and exhibited discrete compositional patterns. Milk microbiota composition and diversity were associated with maternal factors (BMI, parity, and mode of delivery), breastfeeding practices, and other milk components in a sex-specific manner. Causal modeling identified mode of breastfeeding as a key determinant of milk microbiota composition. Specifically, providing pumped breastmilk was consistently associated with multiple microbiota parameters including enrichment of potential pathogens and depletion of bifidobacteria. Further, these data support the retrograde inoculation hypothesis, whereby the infant oral cavity impacts the milk microbiota. Collectively, these results identify features and determinants of human milk microbiota composition, with potential implications for infant health and development.

Selected as top 11 papers of 2019 in Cell Host & Microbe.

Highlighted in Nature News, CBC Radio Quirks and Quarks, National Post, New Scientist, CTV News.

Publication
Cell Host Microbe
Shirin Moossavi
Shirin Moossavi
Postdoctoral Fellow
Meghan Azad
Associate Professor

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