• Steven Reinberg
• Posted May 13, 2021

Good Bacteria Aren't Present in Baby's Gut Before Birth

Bacteria don't set up house in the human gut until after birth, a new study finds.

Gut bacteria are vital for digestion and overall health, but when researchers examined the stool (meconium) from 20 infants collected during breech cesarean deliveries, they found these critical germs show up in the gut after birth, not before.

"The key takeaway from our study is we are not colonized before birth. Rather, our relationship with our gut bacteria emerges after birth and during infancy," said co-senior study author Katherine Kennedy, a PhD student at McMaster University in Hamilton, Ontario, Canada.

Recent studies claiming that gut bacteria appears before birth are controversial. These studies have been criticized for the ways they control for contamination, Kennedy noted in a McMaster news release.

"By including only breech cesarean deliveries in healthy pregnant women, we were able to avoid the transmission of bacteria that occurs naturally during a vaginal birth," said co-senior study author Thorsten Braun, lead obstetric consultant and deputy director of the Department of Experimental Obstetrics at Charite-Universitatsmedizin Berlin.

Data suggest that a person's gut bacteria are most important in early life, during critical stages of immunological and physiological development.

"The fact that colonization of infants' guts occurs during and after their births means that not only is it vulnerable to early environmental influences, but could also offer a window of potential intervention," said researcher Deborah Sloboda, a professor of biochemistry and biomedical sciences at McMaster.

"While many of the exact mechanisms surrounding gut bacteria and their role in our early development is unclear, discovering when and how we are colonized is a key first step," she said in the release.

The report was published May 10 in the journal Nature Microbiology.

More information

For more on gut bacteria and health, see the American Heart Association.

SOURCE: McMaster University, news release, May 10, 2021