• Posted June 15, 2023

'Vaginal Seeding' Could Give Health Boost to Babies Born Via C-Section

Vaginal "seeding" may be a safe way to transfer mom's beneficial bacteria to C-section babies -- and it might help them hit some early milestones a bit sooner, a small clinical trial suggests.

Experts stressed that the findings are early, and it remains to be seen how vaginal seeding -- swabbing newborns with moms' vaginal fluids -- might ultimately affect child development.

And for now, the procedure is one for the research setting.

"This is not something you want to do at home on your own," said Jose Clemente, one of the researchers on the study and an associate professor at Mount Sinai's Icahn School of Medicine in New York City.

Why do it at all?

When babies are born, their journey through the birth canal exposes them to an array of "good" bacteria from mom -- a key first step in building an infant's own gut bacteria collection and educating the developing immune system.

When babies are delivered by cesarean section, however, they miss out on that dose of mom's microbes.

The full consequences of that are unclear, but studies have linked C-section to increased risks of certain childhood health issues related to immune function and metabolism -- including asthma, allergies, type 1 diabetes and obesity.

That -- along with the high rates of C-section in many countries -- has sparked a lot of interest in the concept of vaginal seeding, or what researchers call vaginal microbiota transfer.

Despite the fancy term, it's a low-tech procedure: When a baby is being delivered by C-section, doctors soak some cotton gauze in mom's vaginal fluids then swab her newborn with it.

Vaginal seeding is not part of mainstream medical practice yet. In fact, the American College of Obstetricians and Gynecologists (ACOG) has advised women against the procedure, unless it is being done as part of a medical study.

The new study -- published June 15 in the journal Cell Host & Microbe -- is part of a growing effort to rigorously test vaginal seeding.

The procedure needs to be proven safe as well as effective, Clemente said. The main concern with vaginal seeding is that it could transfer infectious microbes -- including sexually transmitted diseases and group B strep bacteria that can make infants seriously ill.

The new trial, conducted at one hospital in China, involved 68 newborns delivered by C-section. They were randomly assigned to be swabbed with either their mother's vaginal fluids or saline right after birth. For safety, the mothers were tested beforehand for sexually transmitted infections and group B strep.

Over the next six months, the study found, babies who received their mothers' microbes generally showed a faster maturation of their own gut microbiome.

That's the vast collection of bacteria and other microbes in the gut that plays a role in an array of bodily functions, from immune defenses to producing vitamins, anti-inflammatory compounds and even chemicals that influence the brain.

Whether that faster microbiome development might bring benefits is unknown. But the researchers did assess babies' early neurodevelopment: They had parents answer a standard questionnaire about common milestones in the first six months of life -- like laughing, recognizing mom's voice, rolling over and holding toys.

On average, babies in the vaginal seeding group scored 10% higher on those measures at 6 months of age.

It's hard, however, to interpret the significance of that difference, said Dr. Ernest Graham, a professor of gynecology and obstetrics at Johns Hopkins Medicine in Baltimore.

The simple fact is, young infants don't do a whole lot, said Graham, who was not involved in the trial. So no conclusions can be drawn about the effects of vaginal seeding on neurodevelopment, he said.

It's also unclear, Graham added, whether the higher developmental scores were due to the faster maturation of babies' gut microbes.

Clemente agreed, saying the findings "need to be taken with a grain of salt."

"We're talking about very early outcomes," he said. "What will be interesting is to follow these children over time."

Graham pointed to the high rates of C-section in many countries, including the United States, where about one-third of babies are delivered by cesarean.

"It's important to understand the consequences of that," he said.

But it will take additional, larger and longer studies to know whether vaginal seeding is a good counter to any C-section consequences, both experts said.

From a safety standpoint, the trial turned up no negative side effects. But, Graham said, the number of treated babies was too small to declare the procedure safe.

Clemente said he agrees with the ACOG position that vaginal seeding be done as part of a study, and parents might consider enrolling in one if possible.

"This is still in its early stages," he said. Even the way vaginal seeding is done, he noted, is "rather rudimentary."

Going forward, Clemente said, researchers might be able to refine the process -- figuring out which specific microbes are beneficial and should be transferred to babies.

More information

The Cleveland Clinic has more on vaginal seeding.

SOURCES: Jose Clemente, PhD, associate professor, genetics and genomic sciences, and medicine, Icahn School of Medicine at Mount Sinai, New York City; Ernest Marshall Graham, MD, professor, gynecology and obstetrics, Johns Hopkins Medicine, Baltimore; Cell Host & Microbe, June 15, 2023, online