The Good Bugs: Replacing the Microbes that Baby Misses in a C-Section Delivery

in Features, Food Allergy
Published: December 15, 2016

Following is an excerpt from “The Good Bugs” in the Winter 2017 issue of Allergic Living magazine.

Newborn baby right after deliveryGetty Images

Editor’s Note: The first part of the magazine’s article discusses what microbes are and how important they are in our bodies, and how those who used to research “bad” gut bacteria (think E. coli or salmonella) are increasingly coming to understand the importance of “good” bacteria in conditions such as asthma – and how the overuse of antibiotics is changing the health of human beings, and not for the better.

Other factors arresting the role of these important microbes include highly processed foods and sterile urban indoor environments. In the following excerpt from the full article, we hear from Dr. Stuart Turvey, a co-leader of the CHILD population study in Canada, and Maria Gloria Dominguez-Bello, an associate professor of medicine with New York University.


“The more traditional medical view – that bacteria are the enemy and we need to hunt them down, name them and kill them with antibiotics – is changing,” says Turvey, who emphasizes that antibiotics remain essential tools when used sparingly and appropriately.

The new research and the growing awareness of the human microbiome “means we need to change our relationship with bacteria, realize we’ve co-evolved with them and that they’re really important for our health – and be very thoughtful about things like antibiotics,” he says. “So I think the message is: Cherish your bacteria.”

Thanks to the new microbiome research, obstetric specialists are also beginning to cherish bacteria in the birthing process.

It’s long been understood that babies born by C-section are more likely to develop allergic disease and asthma. But now scientists believe they know why: expectant mothers’ vaginal fluids are packed with protective bacteria – and when babies are delivered vaginally, they receive a hefty dose of helpful microbes. Those same microbes then help to fuel the mother’s breast milk.

Dominguez-BelloMaria Gloria Dominguez-Bello

As part of her research into this area, Maria Gloria Dominguez-Bello, an associate professor with the Human Microbiome Program at New York University’s school of medicine, studied the effects of delivery method on babies born at a hospital in the Venezuelan Amazon. Those born through the birth canal had vaginal bacteria in their systems, she noted, but infants born by cesarean were lacking those bacteria. (Interestingly, the C-section babies were shown to have skin bacteria, both from the mother – and from medical staff and hospital cleaners.)

So Dominguez-Bello decided to test a theory: if the highly specific bacteria in the vagina at the time of delivery gives a newborn a head start, would swabbing a cesarean-born baby with vaginal fluids offer that same big immune advantage?

She began with a small pilot study in Puerto Rico involving 18 babies – seven born vaginally and 11 born by cesarean, four of whom received the vaginal fluids in their mouths and on their skin. The results were groundbreaking: the babies born by C-section who received the swabbing (or “seeding”) had a microbial makeup similar to that of the babies born vaginally.

“It’s almost common sense: If you expose a newborn to vaginal bacteria, the newborn picks up vaginal bacteria. But it’s beautiful to see it,” says Dominquez-Bello.

Exactly what roles the various bacteria play is yet to be determined, but the differences in the microbial makeup of babies born vaginally and those born by C-section is so significant that, beyond the age of one month, a researcher can look at a mouth, skin or fecal sample of the child and identify how he or she was born.

The bacteria also play a key role in boosting breast milk. “The composition of the vaginal microbiome of the mothers, and the fact that all mammals drink milk after being born, are not random, separated events. Maternal milk is an amazing, complex substance that is full of compounds that will not only nourish the baby, they will nourish the bacteria, says says Dominquez-Bello. “And I find that fascinating.”

She is now working on expanded studies to measure the health consequences of “seeding” and whether or not it protects against diseases associated with C-section and early antibiotic exposure, such as obesity and diabetes. Still, much more research needs to be done.

In the meantime, she’s regularly fielding calls and emails from patients, doctors and other medical practitioners who are interested in trying the seeding technique. However, she emphasizes that people should not attempt the procedure without first consulting with their doctor.

AL_US COVER Winter 2017“This is not a standard practice. And moms that do it alone could be putting the baby at risk because they don’t know if they have infections,” she says. “So definitely go to your doctor.”


The rest of the fascinating “Good Bugs” article describes advances key researchers are making on microbes and food allergies and asthma; discoveries about the impact of diet and the possibilities of probiotics; and how to be good to our “beneficial bacteria”. See it in the Winter 2017 issue of Allergic Living magazine, available at Barnes & Noble.