Nature · 12 August 2026 · From issue 20
A baby's gut bacteria come mainly from its mother's gut, not birth or milk.
Trishla Sinha, Siobhan Brushett et al., Maternal influences on infant gut microbiome and health, Nature.
A mother's own gut bacteria are the main source of the bacteria in her baby's gut. This comes from a large study that tracked 714 mothers and babies, using 4,526 stool samples from early pregnancy to one year after birth. Breast milk and the birth canal only rarely passed bacteria to babies. How a baby was born and fed shaped its gut bacteria the most, and the mother's gut bacteria helped predict whether her baby got eczema.
The size of the study that tracked gut bacteria from pregnancy through a baby's first year.
One country, observational only, no proof of cause.
Integrity screen: passed (3 checks) Checked 17 August 2026. Retraction record: none. DOI resolves at doi.org. Metadata record found (Nature). Read the source
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