According to a new study published in the journal Cell this month, researchers are suggesting that it's actually fecal-oral transmission during a vaginal birth that improves gut health for babies born vaginally, versus those born by C-section.
Yep, you read that right. Babies born vaginally are "colonized" by bacteria from their mom's feces, not from fluids inside the birth canal. So now there's a biological reason to make peace with the fact that you'll probably poop during labour—it improves your baby's health!
There's been a lot of talk about kids' gut health in the past few years, and you may have heard about how babies born vaginally have healthier guts than those born via C-section, leading to a multitude of long-term health benefits (such as a lower risk of developing allergies, celiac disease and inflammatory bowel disease). It was thought that this healthier microbiome in babies' guts comes via the birth canal and vaginal fluids, which led, in some hospitals, to the practice of vaginal seeding. (However, vaginal seeding or swabbing hasn't been proven to be effective and could even be dangerous.)
In the new study, which followed seven moms and their babies (this is, admittedly, a very small sample size), scientists fed the newborns a sample of their mother's poop diluted in 5 mL of breastmilk. Throughout three months of follow-ups, none of the C-section babies experienced any significant adverse effects. And after the first week, their gut microbiomes "showed significant similarity" to those of babies who were born vaginally. Whoa.
Now this may sound pretty gross—and frankly, it kinda is—but it's not totally unheard of. Fecal microbiota transplants have been used in medicine to treat things such as C. difficile infections and ulcerative colitis since the late 1900s.
Nature actually wants newborns to come in contact with their mother's feces. “There’s a reason the orifice for having babies is next to the anal orifice, in all vertebrates,” Maria Gloria Dominguez-Bello, who is a microbiologist at Rutgers University, told Science magazine. "This is natural selection, not random. It’s a clear message from nature."
Other mammals do their own version of this, too. Fun fact: After six months of drinking their mom's milk, baby koalas will switch to a diet of what's called pap, which is a runny protein-rich poo from their mom, for several weeks. While this may seem disgusting, the pap gives them the gut flora necessary to digest a staple in their adult diets: eucalyptus leaves, which are poisonous when ingested by humans and by most other animals.
Now this should be very, very obvious, but we'll say it anyway: if you gave birth via C-section, do not feed your poop to your baby. This is not a DIY hack you can do at home to improve your newborn's microbiome—it's a controlled study done under strict supervision. In fact, the researchers explicitly state that this kind of fecal transfer "should only be done after careful clinical and microbiological screening."
And besides, with all the diaper explosions happening during the newborn phase, you're probably all pooped out anyways.
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