Study suggests c-section babies don't miss out on vital gut microbes

Do newborns birthed by c-section surgery — through a cut made in the tummy and womb — miss out on vital microbes? The answer appears to be no, according to new research.

The latest findings demonstrated that regardless of delivery mode, evolution has ensured that microbes find a way to be delivered via alternate, compensating routes, if necessary.

The research sheds light on how infants, typically thought of as sterile before birth, acquire the necessary microbes for their diverse microbiomes.

How do C-section babies get their microbiome?

The majority of microbiome research has been on the gut. However, most people don't know that we also have healthy microbial communities in our skin, respiratory tracts, and other areas.

The scientists collected samples from 120 Dutch moms and their newborns regularly to better understand how the microbiome changes throughout the first month of life.

Two hours after the babies were delivered, as well as at one day, one week, two weeks, and one month old, they took skin, nose, saliva, and gut microbiota samples from the infants.

In order to identify which of these sources was "seeding" the various microbiomes of the babies, the scientists also collected six different types of microbiome samples from the mothers: skin, breastmilk, nose, throat, fecal, and vaginal samples.

They next examined these findings in light of several variables, such as delivery method, antibiotic use, and breastfeeding, that are believed to affect microbiota transmission.

"We saw that many niches of the mother are important for the transmission of microbes," explained senior author Wouter de Steenhuijsen Piters in a press release.  

"If some of these pathways are blocked for one reason or another—in this case, we saw that happening with the cesarean section—then these microbes can still reach the infant through other paths.

The researchers discovered that the mother contributes about 58.5% of a baby's microbiota, regardless of the baby's delivery method.

"Evolution has ensured that those microbes are transferred one or another way"

That said, different maternal microbial communities influenced neonatal microbiomes in different ways. For c-section babies, fewer microbes were transferred through their mother's vaginal and fecal microbiomes. But these babies reportedly acquired more microbes from breastfeeding—like, as a form of compensation. 

"Microbiome transfer and development are so important that evolution has ensured that those microbes are transferred one or another way from mother to child," said first author Debby Bogaert, a physician-scientist at the University of Edinburgh. 

The group is now keen on discovering more about non-maternal factors affecting an infant's microbiome development. "We could see that the maternal microbiome explains almost 60 percent of the infant's total microbiome, but there's still 40 percent that we don't know about," said de Steenhuijsen Piters.

"It would be interesting to stratify that unknown fraction to see where all the microbes come from; whether fathers contribute, for example, or siblings, or the environment."

The study was published in the journal Cell Host & Microbe on March 8.