Should C-section babies get wiped down with vagina microbes?

newborn birthed by C-section

Rubbing babies born by C-section with vaginal fluid changes their microbial makeup in a potentially beneficial way, but some doctors caution that the procedure comes with risks. 

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Bacteria is back, baby. After decades of gobbling antibiotics and overzealous hand sanitizing, it’s now clear that the bacteria that live in and on our bodies can help keep us healthy. That realization is what led scientists to rub brand-spanking-new babies with fluid from the mothers’ vaginas.

Like about a third of babies born in the United States, these babies were born by C-section, and so missed out on a trip through the birth canal, where their bodies would have been propelled with viselike pressure through a channel coated with microbe-laden fluid. This crushing, juicy journey coats babies with their mothers’ vaginal microbes. Babies born by C-section are instead colonized with bacteria that live on skin (possibly picked up from the dust in the hospital operating room).

That difference may have important implications for future health, some scientists think.  Studies have hinted that microbes picked up during a vaginal birth can sculpt newborns’ immune systems in ways that combat disorders including obesity, asthma and allergies. So it follows that replacing those missing vaginal microbes might be a good thing.

Scientists led by Maria Dominguez-Bello of New York University and the University of Puerto Rico in San Juan took a first step in testing that idea with the vaginal wipe-down experiment. An hour before a C-section, doctors inserted a square of wet, folded gauze into four women’s vaginas to slurp up the fluid.  This microbe-laden gauze came out right before the C-sections began. Within a minute of birth, the newborns were swabbed with the gauze, first on their lips, then their faces, trunks, arms and legs, genitals, anuses and, finally, their backs. The whole-body rubdown took about 15 seconds.

Those 15 seconds led to bacterial changes that lasted through the newborns’ first month, the researchers reported February 1 in Nature Medicine. Compared with babies born via C-section who didn’t get swabbed, the four swabbed babies had bacterial species on their mouths, skin and guts that were more similar to those in their mothers’ vaginas. That resemblance suggests that swabbing could transform the newborns’ microbes in a way that might ultimately be beneficial.

The study gives some much-needed heft to the idea that microbes matter. By showing that newborns’ bacteria can be manipulated in a pretty simple way, the study opens the door for other tests of whether this microbial rehab is a good thing.  

But the study is preliminary, the authors stress in their paper. The results come from four babies, with only a month of follow-up. It’s possible that these changes don’t stick around. It’s also possible that these microbes don’t actually improve health.

Those outstanding questions haven’t deterred some intrepid parents of babies born by C-section who want to try “vaginal seeding,” says pediatric infectious disease expert Aubrey Cunnington of Imperial College London. Over the last several years, news reports have raised interest, prompting some parents to request the procedure. On neonatal infection rounds last summer, a fellow doctor brought up a troubling story. “She described a recent situation where she had needed to stop a midwife from performing seeding, because the mother had a genital herpes infection,” Cunnington says.

That situation raised an important issue — fluid from a mother’s vagina may carry beneficial microbes, but it could also hold bacteria and viruses that could harm a newborn, Cunnington and colleagues wrote in an editorial published February 23 in BMJ. “Demand has outstripped both professional awareness and professional guidance on this practice,” he and his colleagues wrote in their editorial.

A lack of guidance is worrisome, he argues, because the procedure could unknowingly expose newborns to dangerous bugs, pathogens that babies born by C-section usually avoid. Group B streptococcus, which is carried by about 30 percent of women, can trigger meningitis and fatal septicemia, he says. Herpes simplex virus can lead to death and disability in newborns. And chlamydia and gonorrhea can cause severe eye infections.

Cunnington argues that those potential risks, coupled with unproven and potentially slim benefits, makes the procedure a no-go for now. “On balance, I don’t think the potential benefit outweighs the risk,” he says. Health practitioners at his hospital have been advised not to perform the procedure. (But because the swabbing is so simple, they can’t stop parents, or more realistically, another helper, from performing it themselves.) Staff at other hospitals vary in their willingness to help.

In the swabbing study, the protocol came with built-in safeguards. The women were tested for pathogens, and showed no signs of viral or bacterial infections. And the gauze was handled carefully so that it didn’t pick up new germs. Those precautions should be followed by any hospital or DIYer.

Like any decision — particularly those related to pregnancy and children — choosing whether to swab a baby born by C-section comes with a murky risk assessment. Some of that risk can be lowered by ruling out pathogens such as group B strep and STDs, tests that are usually offered to pregnant women in the United States. Cunnington points out that group B strep test results aren’t always reliable, and that STDs can be picked up after the tests. As a result, looking for those pathogens close to the time of delivery can make microbe swabbing less risky.   

If you don’t feel like an adventurous self-experimenter, you can tend to your newborn’s microbes in other ways. Breastfeeding and avoiding unnecessary antibiotics may both encourage good microbes to flourish, no swabbing necessary. 

Laura Sanders is the neuroscience writer. She holds a Ph.D. in molecular biology from the University of Southern California.

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