Microbes Swabbed from the Mother at Birth Can Speed Up C-Section Babies’ Brain Development, Study Finds

Microbes Swabbed from the Mother at Birth Can Speed Up C-Section Babies’ Brain Development, Study Finds

By three and six months, newborns who had been swabbed with their mothers’ vaginal secretions had attained a higher number of neurodevelopmental milestones than c-section babies who did not get the therapy, according to the results of the randomized, blind study involving 76 children and mothers.

But according to academics, it is unclear whether these variations will be significant or long-lasting.

Microbiologist Jose Clemente, who is also a co-author of the study, says that “This is not going to make a difference between going to Harvard or not. It’s up to future studies to determine exactly what the mechanism is and how can we maximize the benefit.”

The microbiome, or the body’s collection of bacteria in the stomach, on the skin, and everywhere else, is naturally given to newborns by their mothers.

In order to mimic this early exposure, vaginal seeding entails taking a swab of the mother’s vaginal fluids and applying them to the skin of a baby delivered through a c-section shortly after delivery.

The microbiomes of children born vaginally and by c-section vary, according to studies.

C-section newborns showed larger concentrations of opportunistic bacteria in their intestines in the days following delivery and tended to lack common gut microorganisms that would enhance immune function months later.

A team of scientists under the direction of clinical scientist Yan He, recruited women who were scheduled to give birth through c-section and randomly assigned them to have their infants exposed to vaginal swabs or sterile saline.

This study sought to better understand the safety of vaginal seeding and evaluate its potential advantages.

Because the experiment was carried out at the height of the pandemic, women were initially examined for a variety of infectious illnesses that would endanger the health of newborns.

Those who got the vaginal swabs did not have any severe health issues, and their rates of non-serious consequences, such as minor skin conditions and fever, were comparable to those of the babies who received saline swabs.

When the infants were 3 and 6 months old, the team asked their parents to complete a checklist of neurodevelopmental milestones in speech, mobility, problem-solving, and social and personal abilities, such as reaching out for toys as well as smiling at their mirror reflections.

Newborns that got vaginal swabs tended to achieve their milestones a little bit sooner than infants who received saline swabs.

About the result, physician-scientist Alexander Khoruts said that “It’s very exciting and promising.”

Given how much the brain changes as a kid develops, it’s unclear if the neurodevelopmental differences will end up being significant in the long run.

“Early delay by a couple months may not translate into anything meaningful at 18 years,” Khoruts added.

Clinical microbiologist Lars Engstrand believes in the safety of vaginal seeding, with one condition – that the mothers get screened for pathogens, explaining, “That is a really important message to clinical researchers in this field.”

Ye also agrees that the study’s results need to be taken with a grain of salt at this point in time.

“I don’t think our data now has real clinical significance to say ‘yes, you should do this intervention.”

Instead, he claims that it provides him the assurance he needs to start a bigger, longer-term study that will examine if vaginal seeding changes the prevalence of neurodevelopmental disorders like attention deficit hyperactivity disorder and autism spectrum disorder, which population-health studies show are more prevalent in persons delivered through c-section.

The possible advantages of vaginal seeding are the subject of more research. With over 300 volunteers, Engstrand and his colleagues are evaluating its impact on atopic dermatitis, a skin ailment.

Additionally, Clemente is a collaborator in a US research that examines allergies and asthma, and a group led by Maria Gloria Dominguez-Bello, a microbial ecologist, is examining the impact of the study on obesity.

A 2020 study discovered that diluted fecal samples from the mothers of the newborns resulted in gut microbiomes that mirrored those of children delivered vaginally.

This suggests that vaginal swabs are not the sole method to change the microbiomes of c-section kids.

According to Khoruts, such discoveries should encourage scientists to pinpoint the precise bacteria that get transferred to the baby at delivery.


Katherine is just getting her start as a journalist. She attended a technical school while still in high school where she learned a variety of skills, from photography to nutrition. Her enthusiasm for both natural and human sciences is real so she particularly enjoys covering topics on medicine and the environment.

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