How C-Section Babies Could Benefit From (Yes) Vaginal Bacteria

By Michelle DiNicolas

What if these bacteria, far from being deleterious, were actually the secret elixir to the venerable health of a vulnerable population?

I t’s an unpleasant if titillating biological reality that we have an unthinkable amount of bacteria living all over our bodies, inside and out. In fact, 90% of our cells are bacterial cells, outnumbering human cells by an astonishing 10 times.

Perhaps not-so-surprisingly, these ubiquitous bacteria — collectively referred to as the almighty human microbiota — were demonized for a very long time, and we did everything in our power to get rid of them.

But what if these bacteria, far from being deleterious, were actually the secret elixir to the venerable health of a vulnerable population: babies born via cesarian section?

Research published in Nature Medicine, and covered by the likes of The New York Times and NPR, suggests this bacteria may indeed be key to promoting babies’ health following C-sections. The seminal study, led by NYU Associate Medical Professor Dr. Maria Gloria Dominguez-Bello, raises a salient question about the nature of bacteria — while tapping into a long-simmering reproductive health debate.

Scientists are increasingly validating our deeply symbiotic relationship with the bacteria sitting in our gut and on our skin. We literally need bacteria to survive, and multiple studies have uncovered how they influence everything from our immune system and energy balance to mental health.

The first time we encounter these little critters is not in the womb, however, but the moment we are born and first exposed to the cruel external world. While we are developing in utero, we are blithely floating in a decidedly sterile water bath, sans any exposure to bacteria. When it’s time to make our grand entrance and we pass through our mother’s vaginal canal, we collect the bacteria it contains. And yes, this bacteria gets everywhere: in our mouths, in our eyes, and all over our bodies.

While this sounds gross — it’s hard not to wince at the thought of your mother’s vaginal goo all over your face — it turns out that nature knows we need this. In fact, women in their third trimester naturally create more lactic acid-producing vaginal bacteria, just so they can provide their unborn children with a very specific combination of this bacterial goodness.

This initial exposure is what sets in motion our colonization of bacteria on various barrier tissues that protect us from the external world, including the skin and the respiratory, digestive, and urogenital tracts. The bacteria that colonize the intestines immediately after birth, for instance, play a major role in maturation of the intestinal lining, protection against pathogens, and the development of the immune system.

So essentially, though a baby’s bacterial composition seems to balance out over time regardless of delivery method, researchers think that the pioneer bacterial species of a vaginal birth might have a substantial, lasting effect on the body’s immune response.

Which raises a troubling question: what of those babies who aren’t birthed from the vagina at all?

In 1970, just 5% of American children were born via C-section. Today, according to the CDC, approximately 1 in 3 women undergo this surgery, making it one of the most common operating room procedures in the country.

Though C-section rates in the U.S. have stabilized in recent years, the use of this delivery method jumped from 20.7% to 32.9%. between 1996 and 2008. And this trend isn’t just traceable in America; in China, the figure approaches 50%, and in some private clinics in Brazil, it’s nearly 80%.

c section chart
Cesarian delivery rates between 1996 and 2009 (Credit: CDC)

The rise in cesarean sections has generated red-hot controversy among mothers and the medical industry alike, with many questioning the procedure’s increasing use when there is no identifiable cause for it, i.e. potential health risks to mother or child.

A 2008 study published in Clinics in Perinatology noted that:

“Increases in primary cesareans in cases of ‘no indicated risk’ have been more rapid than in the overall population and seem the result of changes in obstetric practice rather than changes in the medical risk profile or increases in ‘maternal request.’”

One theory is that doctors are encouraging women to have a cesarean section for — what else — money. The average cost of a C-section is $28,000, while vaginal deliveries cost a mere $18,000. A working paper published in 2013 by the National Bureau of Economic Research posited that doctors might make a few hundred dollars more for a C-section compared to a vaginal delivery, and a hospital might make a few thousand dollars more. The paper’s conclusion? Obstetricians perform more C-sections when there are financial incentives to do so.

C-section babies are not, as it turns out, completely secluded from bacteria; they are initially exposed to bacteria from the air of the surgery room, as well as skin bacteria from the mother, surgeons, and nurses. Vaginally delivered babies are also exposed to all these bacteria, but only after they’ve been additionally inoculated with their mother’s vaginal bacteria.

Lactobacillus, aka vaginal bacterial goodness (Credit: Wikimedia Commons)

As a result, researchers have found that the bacterial composition of cesarean section babies have a reduced level of specific types of healthy-baby-making bacteria such as lactobacillus, firmicutes, bifidobacteria, and bacteroides compared to vaginally delivered babies immediately after birth and in subsequent months.

Cesarean section babies have also been shown to possess a lower richness and diversity of bacterial species compared to vaginally delivered babies.

Recent evidence indicates increased risks of allergies, asthma, type I diabetes, and celiac disease in C-section babies as well. And in many cases, a dearth of bacteria has been the decided culprit; one study describes how giving children lactic acid-producing probiotics until the age of five or six reduced their incidence of certain allergies only if they were delivered via a cesarean section. This means that initially, these C-section children lacked the appropriate microbial composition to combat these allergies.

Moreover, planned cesarean sections have been correlated to a higher incidence of allergies compared to an acute or emergency cesarean section. During an emergency cesarean section, the fetal membrane is commonly torn since the mother’s water has already broken. This allows her vaginal bacteria to spread to the fetus. In planned cesarean sections, rupture of this fetal membrane is extremely rare, so the babies never get to interact with the vaginal bacteria.

It’s a bleak situation.

Which is why, at the University of Puerto Rico in San Juan, Dr. Dominguez-Bello and her team of collaborators tried to alter the microbiota of cesarean section babies by exposing them to the glorious goo that is their mother’s vaginal bacteria.

Prior to a planned cesarean section, their team placed a sterile gauze inside the mother’s vagina for one hour, allowing it to soak up as much vaginal splendor as possible. Then, when the baby was born, they immediately cleaned it with that gauze.

Next came the analyses; Dr. Dominguez-Bello compared the composition of the swabbed C-section baby’s bacteria over time against those of vaginally delivered babies and regular (un-swabbed) cesarean section babies. Her team hypothesized that those babies who’d been “cleaned” with vaginal goo would possess a bacterial profile more similar to vaginally delivered babies than to regular cesarean section babies.

Dr. Maria Dominguez Bello

The effects proved to be promising. “These results show that we can partially restore and normalize the microbial assembly that takes place naturally in babies,” Dominguez-Bello told NPR. “We normalize their microbiome.”

When I spoke to Dr. Dominguez-Bello last fall, she told me she and her team were looking to expand their research to other countries such as Bolivia, Ecuador, Stockholm, and Chile. She also said they would be doggedly recruiting mothers having elective cesarean sections and explaining the concept of why babies should be born with the right set of bacteria.

In the wake of continued studies, Dr. Dominguez-Bello said she believes that swabbing C-section children with vaginal bacteria could become mainstream practice in the U.S. and all over the world. Through this work, she and her team also hope that women will learn more about the importance of the human microbiota and potentially opt for a vaginal birth when possible.

“Nature is always right. Nature is so clever,” she told me. “After so many years of evolution, [if] we break natural laws, we are going to pay a price.”

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