Babies usually get a dose of microbes from their mothers during birth, but caesarean section babies miss out with fears this may affect the microbiome and the health of the infants.
But a new study published in Cell Host & Microbe has suggested this may not be a problem: caesarean-born babies can make up that microbial diversity from other sources, like breastfeeding.
“We saw that many niches of the mother are important for the transmission of microbes, and if some of these pathways are blocked for one reason or another – in this case, we saw that happening with the caesarean section – then these microbes can still reach the infant through other paths,” says senior author Dr Wouter de Steenhuijsen Piters, a physician and data scientist at the University Medical Center Utrecht, Netherlands.
The researchers took microbiome samples from 124 babies at several points in their first month of life, as well as their mothers. The group included 49 babies born by caesarean section and 75 by vaginal birth.
They collected skin, nose, saliva, and gut microbiome samples from the infants, and skin, breastmilk, nose, throat, faecal, and vaginal microbiome samples from the mothers.
Regardless of birth, the babies had the same amount of microbiome coming from their mothers. Caesarean babies had less faecal and vaginal maternal microbes, but they made up for this by getting more microbes from breastmilk.
“It’s a smart system, and it makes sense from an evolutionary perspective that these types of pathways are redundant to ensure that the child can begin life with the appropriate ‘starter kit’,” says de Steenhuijsen Piters.
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But maternal microbiome only accounted for 58.5% of infant microbiomes on average.
“We could see that the maternal microbiome explains almost 60% of the infant’s total microbiome, but there’s still 40% that we don’t know about,” says 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.”