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A growing number of soon-to-be parents planning for a cesarean section are also asking for a newer secondary procedure: wiping the newborn with mom’s vaginal fluids. The hope is that vaginal swabbing could restore the microbiomes of babies that miss out on the birth canal. But doctors are cautioning that little research has been done on the procedure, and the risks and benefits aren’t clear.

“It’s not really right to expect a health professional to do something that isn’t of any proven benefit and may carry a risk of harm,” said Dr. Aubrey Cunnington, an infectious diseases specialist who penned an editorial on the subject published Tuesday in the British Medical Journal.


The risk is that mothers may be carrying certain viruses or bactera — like the ones that cause chlamydia and genital herpes — and not realize it. Babies born by C-section are typically spared exposure to those viruses, but the swabbing could reintroduce that risk. It’s also unclear if the procedure has any negative long-term effects on a baby’s health, since no longitudinal research has been done on the subject.

A study published earlier this month in Nature Medicine found that swabbing babies born by Cesarean section with microbes collected from their mothers could help them develop healthier microbiomes — the colonies of microorganisms in the human gut, mouth, and skin. In that study, doctors swabbed four babies in the first few minutes after delivery with gauze coated with their mother’s vaginal fluids. Thirty days after birth, those babies had more diverse microbiomes, more similar to babies born vaginally. It’s suspected that a less diverse microbiome might have negative effects on a child’s health.

Still, a long-term study of a large group of infants who’ve been vaginally seeded is needed before clinical use. “We advise doctors not to do this procedure, but mothers could well do this themselves,” Cunnington said.


If parents take the DIY approach, Cunnington said it’s crucial they let their child’s doctor know. Take, for example, babies exposed to chlamydia during birth; they often turn up with nasty eye infections. Doctors might think babies are safe from chlamydia because of a C-section delivery — when, in fact, the baby was swabbed with vaginal microbes.

“If they don’t know this vaginal seeding was done, they may make the wrong call,” Cunnington explained.

Dr. Juliette C. Madan, a neonatologist at Dartmouth-Hitchcock Medical Center who has studied infant microbiomes, said she agrees with Cunnington and other groups urging caution when it comes to vaginal swabbing. If the procedure turns out to boost babies’ microbiomes in the long run, Madan said doctors would need to thoroughly screen women to make sure there’s nothing that could be passed to a newborn via vaginal swabbing. Such screenings are common in the United States when women are 36 weeks pregnant, but not in other countries.

“You don’t want to do any intervention — because it’s time-consuming and there might be risks — if there are no benefits,” she said.

Until there’s more evidence, Cunnington said, it’s best to encourage new mothers to focus on breastfeeding their infants and avoiding unnecessary antibiotic use to promote healthy microbiomes in their babies.