Babies born vaginally get exposed to important bacteria as they pass through their mothers' birth canals -- bacteria that helps their immune systems develop. But babies born by Caesarean section miss out on some of these beneficial microbes, which some worry may leave them more susceptible to health problems down the road.
Researchers wanted to test whether it's even possible to transfer mothers' vaginal bacteria to babies born by C-section, and published on Monday their small, proof-of-principle study in the journal Nature Medicine.
"Our study is the first to demonstrate that partial microbiome restoration just after birth is possible in babies born by C-section," Maria Dominguez-Bello, lead study author and microbiologist of New York University's Langone Medical Center, said in a release. "With a third of U.S. babies now born by C-section, twice the number as is medically necessary, the question of whether a baby's founding microbiome affects its future disease risk has become more urgent."
For the study, researchers took samples from seven vaginally born babies and 11 delivered by C-section. Four of the babies born via C-section were swabbed with their mothers' vaginal fluids.
Just minutes after they were born via C-section, four of the babies had their mouths and bodies swabbed with vaginal fluids that had been taken from their mothers just an hour prior to birth.
During the first 30 days, those swabbed babies had microbes that more closely resembled vaginally born babies than non-swabbed C-section babies. Lactobacillus and Bacteroides, bacteria that's been shown to help infant immune systems develop so that they don't attack helpful bacteria, were found in higher numbers on the vaginally born and swabbed babies.
The study authors emphasize they don't know what the long-term health outcomes are for these babies. More research involving many more babies and mothers will be needed to know what, if any, benefits there are from swabbing babies born via C-section.
"Larger studies that measure the effect of early microbiome restoration on health outcomes would begin to answer whether or not it averts future disease risk," Dominguez-Bello said. "The current study represents proof of a principle in a small cohort, and shows that our method is worthy of further development as we seek to determine the health impact of microbial differences."
Although small, the finding has intrigued scientists not involved in the study. Dennis Kasper, a microbiologist and immunologist at Harvard Medical School, told Science Magazine it represents "a very interesting and simple intervention."
“The study is extremely important,” Jack Gilbert, a microbial ecologist at Argonne National Laboratory, told the New York Times. “Just understanding that it’s possible is exciting.”
Some parents have even been requesting to have their babies swabbed, but dangerous bacteria could get transmitted in the process. For this study, women were screened for pathogens and co-author Jose Clemente told NPR "don't try this at home."
Jacques Ravel, associate director of the Institute for Genomic Sciences at the University of Maryland, cautioned that for now, "don't do it. We just don't know enough," the Associated Press reported. "Not all vaginal microbiota are equally good."