Seeding the infant microbiome after a C-section

I was very excited today when I saw that Nature Medicine published a study entitled, “Partial restoration of the microbiota of cesarean-born infants via vaginal microbial transfer“. I have been waiting to hear about how microbial transfer after a C-section affects babies ever since I found out that Dr. Maria Dominguez-Bello, a prominent human microbiome researcher, was conducting a clinical trial at NYU where infants who were delivered by C-section (rather than vaginally) were then swabbed with their mother’s vaginal microbiota. Though Dr. Dominguez-Bello is an author, this particular paper analyzes a group of mothers and babies living in Puerto Rico, while I believe the NYU trial is on-going. Over the last few years, a number of studies have shown that the gut microbiota of infants delivered by C-section is different from the gut microbiota of infants delivered vaginally, and that over the period of a few years, children delivered by C-section are more likely to suffer from obesity, allergies, and asthma. I’ve even seen this gut bacterial difference in premature infants in my own work.

Swabbing the infants with the maternal vaginal bacteria did not perfectly recapitulate a vaginal delivery, but their gut bacteria did more closely resemble that of vaginally delivered babies compared to those delivered via C-section. The published paper used a small number of subjects, and whether the swabbed infants receive protection from obesity, allergies, or asthma is still to be determined. But benefits have been shown for infants whose mothers labored before undergoing a C-section (for example, imagine the baby was trying to come out of the canal feet first, could not get turned around head first, so then had to removed by C-section). The thought is that these infants were exposed to the vaginal microbiome during labor, even though they did not successfully come out of the vaginal canal (I can’t seem to find a link to this at the moment).


Swabbing after a Caesarean delivery (Image from Nature Medicine’s Facebook. Kim Caesar/Nature Publishing Group)

Hopefully we will see the effects of the swabbing in the coming years, and if the results are positive, swabbing could become a routine part of the delivery process (or we will use probiotics once we figure which bacteria are most beneficial to the child immediately after birth). The danger associated with swabbing is that some mothers are infected with viruses (Herpes) or bacteria (Group B Streptococcus) that could harm the infant, and these microbes could be transferred to the child through the swabbing. Generally, mothers are given medication (antibiotics or anti-virals) if they test positive for these “bad” microbes before they deliver their baby. However, if a mother does not have adequate pre-natal care (i.e. we don’t know about her infection status), swabbing would be considered risky.

Interestingly, I found this in the paper:

Competing financial interests

New York University has filed a US patent application (number 62161549) related to methods for restoring the microbiota of newborns on behalf of M.G.D.-B.

More links to check out:



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