Microbiota of the human intestine, illustration

New research by a team of Chinese, Canadian, and U.S. researchers has found that seeding newborn babies who are born via C-section with their mother’s vaginal bacteria improves neurodevelopment in the first months of life. The research, published last week in the journal Cell Host & Microbe, suggests this can be a viable method to improve the microbiota of babies born via C-section.

Past research has demonstrated that babies born by C-section have a significantly different population of gut bacteria than those delivered vaginally. Those born via a C-section get their bacteria primarily from their mother’s skin, breast milk and their environment, while babies born vaginally receive their early gut bacteria from those present in the mother’s birth canal. These differences largely disappear with age, but researchers have suggested that microbiota present early in a baby’s life can affect the development of a baby’s immune system and affect risk of developing diseases later in life.

This knowledge has led in some cases to vaginal microbiota seeding whereby mothers would rub their C-section newborns with their vaginal fluids. However, with limited clinical evidence of whether this is effective, the team behind the new research set out to determine what effect, if any, this practice may have on babies early in life.

“When we talk about effectiveness, we not only mean whether this intervention might affect the infants’ microbiota but are also interested to see if this intervention could actually improve the infants’ phenotypes, like their neurodevelopment,” said corresponding author Yan He, PhD, a professor at Southern Medical University in Guangzhou, China.

The team’s research cohort comprised 68 newborns delivered via C-section. He and team rubbed the lips, skin, and hands of 32 babies with gauze soaked in their mother’s vaginal fluids, while the 38 control babies were rubbed with gauze soaked in saline. All the mothers were tested in advance to ensure they were free from infections.

The result showed that the babies who had received their mother’s microbiota from their mother’s vaginal fluids showed more of that bacteria in their gut, suggesting that the method of seeding used by the researchers effectively reached and colonized the babies’ guts, with no adverse events reported. Further, the babies who had been received microbial seeding had more mature bacteria in their gut at levels similar to vaginally delivered babies.

In addition, the investigators sought information on the early neurodevelopment of the babies via questionnaires completed by their mothers at three months and six months. Questions related to babies making simple sounds, or performing movements such as crawling, were used as measures of their neurodevelopment. Again, the seeded babies scored significantly higher than the control group for neurodevelopment at both the three-month and six-month marks, and were comparable to vaginally delivered babies.

“We don’t know exactly how early gut bacteria affect their neurodevelopment, but there is some indirect evidence that shows some microbial metabolites are related to conditions,” He noted. As an example, the researchers found that babies who received vaginal microbiota seeding had more indolelactic acid—a type of metabolite of several Clostridium bacteria species—in their feces. Previous research has discovered that indolelactic acid levels are low in people with Parkinson’s disease and Alzheimer’s disease.

He said that they hope his team’s new findings will spur other groups to conduct similar research to discover whether vaginal microbiota seeding of C-section babies can reduce the risk of neurodevelopment disorders in children such as ADHD or other intellectual disabilities.

“It is somewhat like fecal microbiota transplantation. We need more data to understand this intervention and make it more precise. We may eventually uncover what exactly is beneficial in maternal vaginal microbiota, which could enable us to design therapeutics for all infants born via C-section in the future,” He concluded, noting that his team is already planning long-term studies with larger sample sizes to confirm their findings.

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