Clinical Edge

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Study challenges role of birth canal exposure in newborn microbiome establishment

Key clinical point: During transmission of gut bacteria from mothers to infants, the dominant maternal source of bacteria is rectal, and not vaginal.

Major finding: Out of 24 babies with persistent Bacteroides colonization in the gut, 22 (92%) were born vaginally, compared with 2 (8%) born via pre-labor C-section (not exposed to birth canal), and none born via post-labor C-section (exposed to birth canal).

Study details: A longitudinal trial involving 73 mothers and their newborns.

Disclosures: Dr. Yassour disclosed no conflicts of interest.


Yassour M et al. GMFH 2020.