What Is ‘Vaginal Seeding’? Medical Doctors Explain

Updated: Jul. 06, 2023

Vaginal seeding is an emerging practice that research says is showing promise in one particular area of health, according to a new study. Here's why doctors say you should still be cautious.

Cesarean sections have revolutionized the landscape of childbirth, offering a vital lifeline when complications arise. However, emerging research hints at a potential hiccup with this life-saving procedure: A gap in bacterial exposure for the newborn. Enter “vaginal seeding,” a practice that aims to rectify this bacterial imbalance. Vaginal seeding is a practice that obstetrics and pediatric researchers say could solve the issue—but here are the main questions at this point in the science.

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The what and why of ‘vaginal seeding’

During the process of vaginal births, infants encounter diverse bacteria in the mother’s birth canal, offering an important start to their microbiome—the unique community of microorganisms in our bodies. However, this process is bypassed in cesarean deliveries.

Vaginal seeding is a procedure designed to bridge this gap. Following a C-section, a swab soaked in the mother’s vaginal fluid is passed over the baby’s mouth, face and body, mimicking the bacterial exposure of vaginal delivery and, thus, “seeding” the baby’s microbiome. Proponents of vaginal seeding believe that this can be beneficial in preventing certain conditions such as asthma and allergies.

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Research, findings, and future perspectives

Vaginal seeding is garnering interest, fueled by recent research published in June 2023 in the peer-reviewed journal Cell Host & Microbe. This blinded, randomized, controlled trial focused on the effects of vaginal seeding on cesarean-born infants. The research involved swabbing newborns with either their mother’s vaginal fluids or a saline solution immediately following birth. The preliminary findings suggest that infants swabbed with their mother’s microbes displayed an accelerated maturation of their gut microbiome.

However, Jose Clemente, PhD, a study author and an associate professor at the Icahn School of Medicine at Mount Sinai in New York City, urges a cautious interpretation of these early results. Acknowledging the infancy of the study, Dr. Clemente emphasizes the need for longitudinal studies to assess the long-term effects of vaginal seeding. “We’re talking about very early outcomes,” he says, pointing out the necessity to monitor these children’s development over time.

Early results indicate that the infants in the vaginal seeding group had higher scores on early neurodevelopmental milestones at six months of age. However, these associations require further exploration through more extensive and extended studies to fully determine the impact of vaginal seeding in counterbalancing any effects of cesarean sections.

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Concerns and recommendations from the medical community

While the potential benefits of vaginal seeding are promising, the medical community maintains a cautious stance due to limited data on its safety and efficacy. For instance, the American College of Obstetricians and Gynecologists (ACOG) advises against performing vaginal seeding outside of research contexts.

A primary concern is the risk of transferring harmful pathogens from mother to infant during the procedure. While the intention is to populate the baby’s microbiome with beneficial bacteria, there’s a potential for unwanted, even harmful, microorganisms to be introduced as well.

To ensure the safety of both mother and child, ACOG recommends rigorous testing for infectious diseases if a patient insists on the procedure. Thorough counseling on the known risks associated with vaginal seeding is also emphasized. The aim is to equip parents with comprehensive information, enabling them to make informed decisions about their newborn’s health.

In a 2017 news release, Dr. Christopher Zahn, an OB/GYN and then-interim CEO for ACOG, emphasized the importance of breastfeeding in shaping an infant’s gut microbiome. “Breastfeeding for the first six months is the best way to overcome the lack of exposure to maternal vaginal flora at birth,” he explained. This is because breast milk and the bacteria present on the nipple naturally seed the infant’s gut. Dr. Zahn further noted that while initial differences might exist in the gut microbiota of infants based on the delivery mode, such differences tend to fade away by around six months, as research has shown.

Dr. Clemente’s perspective aligns with ACOG, proposing that vaginal seeding should be primarily conducted within research studies. As the science around vaginal seeding evolves, Dr. Clemente expresses optimism for the future. He envisions upcoming studies identifying specific beneficial microbes for transfer, enhancing the precision and efficacy of vaginal seeding. These improvements could significantly optimize the practice and its potential benefits for cesarean-born infants.

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