Vaginal Seeding: To Swab or Not To Swab?

By Dr. Eva Martin of Elm Tree Medical

Many mothers-to-be may find themselves pondering a question they never imagined: If I have a c-section, should I swab my vaginal fluid into my baby's mouth? Likewise, many OBGYNs find themselves searching for an evidence-based answer. To swab or not swab? That is the question.

For those unfamiliar with the new practice of "vaginal seeding," you may be asking yourself, "Wait! Why?!" It all started when researchers discovered interesting differences in the microbial colonization (make-up of bacteria in the body) in babies born by vaginal delivery and those born by cesarean section. Infants born by vaginal delivery have a microbiome more similar to the mother's vagina. Infants born by cesarean delivery have a microbiome more similar to the mother's skin.

Does this difference in bacteria in infancy matter? Long story short- we don't know. Some research has pointed to a slightly higher increased risk of asthma, obesity, and autoimmune disorders in those born by cesarean section. Does a baby's skin-like microbiome cause this increased risk? We have no idea. Nevertheless, the difference exists, and somewhere along the way, someone decided to try to change it. They took a swab of vaginal fluid from the mother and transferred it to the baby.

Until recently, we didn't have evidence that this practice, known as vaginal seeding, could or would change the baby's microbiome. After all, an infant spends a lot of time in the birth canal during a vaginal delivery; could one swab replicate this? In July 2015, the online journal Nature Medicine published a Proof of Concept study from Maria Dominguez-Bello, PhD and her colleagues at New York University. The study was small- only 18 babies, but showed that infants born by cesarean section who received vaginal seeding had a microbiome more enriched in vaginal bacteria than those born by cesarean section who did not receive vaginal seeding. Vaginal seeding delivered only partial results, though- the swabbed babies' microbiomes were not identical to those born by vaginal delivery. The authors followed the infants for the first thirty days of life, so we do not yet know if vaginal seeding will have any long-lasting effects on the infants' microbiomes. Most importantly, we don't know if long term health outcomes- like obesity or asthma- will be affected at all.

Expecting mothers may now be wondering, "OK, so maybe it works, maybe it doesn't. What's the harm in trying?" An editorial in the British Medical Journal by Dr. Cunnington, a pediatric specialist in infectious diseases, recently recommended against vaginal seeding. He sites two reasons: (1) There is not enough evidence that it works, and (2) you may transfer an unrecognized infection to the newborn. Some potential infections are Group B Streptococcus, HIV, chlamydia, gonorrhea, or herpes viruses. 25 to 30% of women carry Group B Strep, and infection at birth can cause permanent disability or even death. Chlamydia and gonorrhea can cause conjunctivitis in newborns. About 20% of pregnant women carry antibodies to the Herpes-2 virus, but only 5% have had a symptomatic infection. Herpes infection in the newborn can cause seizures, spasticity, learning disabilities, and even death.

So, what can women and healthcare providers do to promote early microbiome development for infants? First- Breastfeeding! The benefits of breastfeeding are practically endless, and this is one of them. Second- avoid unnecessary antibiotics, which can wipe out the good bacteria along with the bad. Other practices that may help are delaying the first bath for 12 hours after birth, introducing skin-to-skin contact in the operating room, and enabling moms to start breastfeeding in the operating room.

Some hospitals- like the University of Wisconsin-Madison- have created protocols to increase the safety of this procedure for mothers who request it. They screen mothers for Group B Strep, HIV, genital herpes, chlamydia, and gonorrhea. They also promote the other practices that may support the baby's developing microbiome.

All said, we have a lot yet to learn about vaginal seeding. Do the changes in babies' microbiomes last more than a few days? Do these changes have any effect on long-term diseases like asthma or autoimmune disorders? We need large studies, completed over many years. Unfortunately, in this case, only time will tell if it is best To Swab or Not To Swab.