In recent years, more than 1 in 3 babies in the U.S. have been born via cesarean delivery. While c-sections are often medically necessary and lifesaving, they may come with some unexpected long-term health risks for babies. Research has shown that cesarean birth is associated with a higher risk of certain conditions—including obesity, allergies, and even some neurodevelopmental concerns—possibly due in part to differences in how babies born via c-section are first exposed to helpful bacteria.

But what if there was a way to restore some of the beneficial bacterial exposure that babies miss out on during a cesarean birth? That’s where some researchers think vaginal seeding may play a role.

What is vaginal seeding?

During a vaginal birth, babies are naturally exposed to their mother’s microbiome as they pass through the birth canal. This early exposure helps populate the baby’s skin, mouth, and gut with beneficial bacteria that play a big role in shaping the immune system, digestion, and even brain development.

In a c-section, however, this exposure doesn’t happen. Instead, babies born surgically are more likely to be colonized by bacteria from the skin and hospital environment, which may alter how their microbiome develops.

Vaginal seeding is a practice that aims to bridge that gap by manually exposing cesarean-born babies to the same helpful microbes they would have encountered during a vaginal birth. The process is simple: Before a c-section, a sterile gauze is placed in the mother’s vagina. Right after the baby is born, that gauze is used to gently wipe the baby’s mouth, face, and body—delivering a dose of maternal microbes to kickstart the baby’s microbiome.

Does vaginal seeding really work?

Studies show that vaginal seeding can shift a baby’s microbiome closer to that of a vaginally born baby. In other words, it seems to work—at least when it comes to bacterial exposure.

In fact, a 2023 randomized clinical trial published in Cell Host & Microbe found that vaginal seeding successfully transferred maternal bacteria to the baby. And that’s not all: In a 2024 study using a mouse model, researchers found that mice inoculated with stool from vaginally seeded babies had lower levels of intra-abdominal fat, the type of fat associated with metabolic issues later in life. While the results of mouse studies don’t directly translate to human outcomes, this research suggests that early microbial differences could have long-term implications for health and metabolism.

What about other health outcomes and vaginal seeding?

While early findings are promising, research is still catching up when it comes to big-picture outcomes like reducing obesity, asthma, or allergies. One small clinical trial didn’t find a difference in allergy or BMI outcomes between babies who received vaginal seeding and those who didn’t—but more studies are underway.

Several large trials are currently in progress, looking at whether vaginal seeding can prevent the kinds of inflammatory and metabolic issues often linked to c-section births.

Experts hope that as data emerges, we’ll get a clearer picture of whether this simple intervention could ever lead to long-term health benefits.

Is vaginal seeding safe?

In the studies so far, vaginal seeding appears to be safe when done carefully and under clinical guidance. Still, it's not without controversy. One of the biggest concerns is the potential for transmitting infections such as Group B Streptococcus (GBS), herpes simplex virus (HSV), chlamydia, and HIV from mother to baby during the seeding process. These infections can have serious, even life-threatening consequences for newborns.

Because of these risks, the U.S. Food and Drug Administration (FDA) regulates vaginal seeding as an investigational procedure, and it is generally only available through approved clinical trials.

The American College of Obstetricians and Gynecologists (ACOG) does not currently recommend vaginal seeding outside of a research setting, citing insufficient evidence of benefit and the potential for harm. In a 2017 committee opinion, ACOG emphasized the importance of screening for infectious diseases and discouraged informal or unsupervised use of vaginal seeding.

“Given the potential risks and the lack of evidence regarding benefit, it is recommended that patients not perform vaginal seeding outside of a research protocol,” ACOG states.

Researchers advise families not to try vaginal seeding outside of a carefully controlled medical setting until more is known about its safety and effectiveness.

What’s next for vaginal seeding and c-section research?

As the science of the microbiome evolves, researchers are exploring other approaches to help babies born via cesarean delivery establish a strong, healthy gut microbiome. These include:

• Fecal transplant from mother to baby, which has shown promise in restoring gut microbial diversity
• Oral administration of vaginal fluids, which in preliminary findings did not improve gut microbiome development

In the future, scientists hope to create safe, targeted microbial therapies—like a “microbiome starter kit”—for newborns who can’t receive vaginal seeding.

Meanwhile, practices like breastfeeding, skin-to-skin contact, and minimizing unnecessary antibiotics remain excellent ways to support your baby’s microbiome health.

The Bottom Line on Vaginal Seeding

Vaginal seeding is an intriguing and potentially promising method of restoring early microbial exposure for babies born by c-section. While the research is still unfolding, current evidence suggests it may benefit early brain development and metabolism.

For now, experts recommend that vaginal seeding only be done in the context of a clinical trial. But with more research on the way, this simple, low-cost practice could someday become a powerful tool to help cesarean-born babies get the healthiest start possible.

More on C-Sections:

• C-Section Recovery Essentials
• How to Help Your Body Heal After a C-Section
• What I Wish I Knew Before My C-Section and VBAC

 

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REFERENCES

• Air Pollution and Its Effects on Human Health: Advances in Air Pollution Research, International Journal of Environmental Research and Public Health, November 2020
• Bacterial Metabolism of Host-Derived Nutrients Shapes the Gut Microbiota, Proceedings of the National Academy of Sciences, August 2010
• Breaking the Silence: Antibiotic-Induced Changes to the Microbiota and Their Impact on Health, Cell, June 2014
• Disruptions in the Gut Microbiome Contribute to Increased Susceptibility to Infection, mBio, May 2023
• Effects of Early-Life Antibiotic Use on the Developing Microbiome, Cell Host & Microbe, May 2023
• Functional Foods and Gut Microbiota: A Review on the Potential of Prebiotics and Probiotics, Microbial Ecology in Health and Disease, February 2024
• Gut Microbiota Composition and Risk Factors in Pregnancy, American Journal of Obstetrics & Gynecology Maternal-Fetal Medicine, October 2022
• Infant Gut Microbiota Development and Its Implications for Health, JAMA Pediatrics, February 2024
• The Role of the Gut Microbiota in Metabolism, Cell, August 2020
• The Vaginal Microbiota of Pregnant Women and Its Impact on the Newborn, Cell, November 2020
• The Vaginal Microbiome and Preterm Birth, Cell Reports Medicine, September 2021

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