Newborns have different bacteria, viruses, and fungi in their guts depending on whether they were born vaginally or by Caesarean section — and the latter group is at a stark disadvantage. The difference in these gut microbes, collectively called the microbiome, could have long-term impacts on C-section babies’ health, particularly on their risk of developing immune-related disorders like allergies, inflammatory bowel disease, and celiac disease. But C-section babies who are fed breast milk with mom’s poop in it develop the same microbiomes as vaginally delivered babies, according to a new study.
Babies are born without much of a microbiome. They typically pick up microbes during vaginal delivery, but C-section babies miss out on this “bacterial baptism,” as some call it. Studies have tried to recreate this germ-y moment by swabbing C-section babies in microbes from their mother’s vagina, but it doesn’t work well. For a better match, you have to look further south.
“The bacteria that you find in the baby [gut] are not found in the vagina, so it’s not so likely it’s the source,” Willem de Vos, a microbiologist at the University of Helsinki and Wageningen University, told The Scientist. “It’s more likely that there is a fecal-oral transfer” during delivery, he says, because it’s “a messy business.”
The new study, led by de Vos, imitated this transfer by putting a small amount of the mother’s feces — a few million bacterial cells worth — in the newborn’s first gulps of breast milk via bottle. Doctors watched over the babies for two days in the maternity ward and followed up at four weeks and three months. They also checked the babies’ poops throughout that time to keep track of their microbiome development.
The researchers included seven mothers and their C-section babies, whose microbiomes were compared to 29 vaginally delivered babies and 18 untreated C-section babies. After three weeks, the treated babies’ microbiomes resembled those of babies born vaginally. That’s a big deal because usually it takes C-section babies a full year to get their guts up to speed. And at least within three months, none of the treated babies developed adverse health effects.
“There’s a reason the orifice for having babies is next to the anal orifice, in all vertebrates,” Maria Gloria Dominguez-Bello, a microbiologist at Rutgers University, New Brunswick, who was not involved in the study, told Science. “This is natural selection, not random. And it’s a clear message from nature telling us, ‘We want the newborns to be exposed to feces.’”
While the study is promising, it’s small and needs more research to confirm its findings. No one should be trying this on their baby yet — especially not at home. De Vos and his fellow researchers have started a follow-up randomized control study that will give dozens of C-section babies either their mother’s feces or a placebo. Afterwards, the researchers will follow the children’s health over several years. De Vos recommends no one DIY this experiment at home before more data is available.
One of the questions the researchers will need to answer is how much poop is the right amount of poop. “We don’t know how much babies ingest naturally, so getting the right dose requires careful testing,” John Penders, a medical microbiologist at Maastricht University, told Science. Until then, waiting for more data before you make your baby eat feces is definitely the right approach.