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Only a 30 day-follow-up of 4 vaginally seeded scheduled C-section babies in one pilot study has been published so far (1). This study showed that vaginal seeding of these 4 babies had partial restoration of their microbiome, i.e., resembled more those of vaginally delivered babies rather than C-sections. A recent BMJ comment (2) points out that currently vaginal seeding has only one small (n=78) clinical trial listed on Home – ClinicalTrials.gov (3).

It’ll take several years at a minimum to decades to show long-term effects of vaginal seeding just as it took that long to show C-section deliveries are associated with long-term higher risk of allergy, asthma and autoimmune disorders. That said, there are issues as well with vaginal seeding that should be discussed as there’s great interest in the process even as there’s little scientific data on it.

Problems with vaginal seeding as it’s being tested today

  • Can’t lump different types of C-sections together. Scheduled and emergency C-sections are different in kind. Emergency C-sections usually happen after labor. Thus, their vaginal hormonal milieu (and likely microbiota) are different, in fact, resembling vaginal births more than scheduled C-sections, which are planned and usually pre-labor. Could vaginal seeding even be equivalent between these fundamentally different types of C-sections?
  • Unlike vaginal deliveries, antibiotic Rx is standard-of-care for C-section mothers. Undoubtedly ante- and intrapartum antibiotics change vaginal microbiota. How does that affect newborn colonization of such vaginally seeded babies born via C-sections?

Additional concerns

  • Need to test vaginal secretions for group B streptococcus, herpes simplex virus, Chlamydia trachomatis, Neisseria gonorroheae, microbes the mother may be carrying asymptomatically but which may be very harmful to a newborn. However, since antibiotic Rx is standard-of-care for C-sections, it would go some way in mitigating this concern.
  • No large, long-term clinical trial data on vaginal seeding yet.

Study of vaginal seeding is a kind of catch-22. It may be most useful for emergency C-sections. However, by their very nature such procedures can’t be planned ahead. So clinical trials would probably study vaginal seeding of scheduled C-sections instead, which may be of dubious value anyway since they don’t involve labor. OTOH, C-sections have been increasing for decades and they’re not all medically necessary. Concerns about long-term adverse health consequences of C-sections could be reduced more simply by just reducing the number of medically unnecessary C-sections.


1. Dominguez-Bello, Maria G., et al. “Partial restoration of the microbiota of cesarean-born infants via vaginal microbial transfer.” Nature medicine (2016). https://www.researchgate.net/pro…

2. Cunnington, A., et al. ““Vaginal seeding” of infants born by Caesarean section. How should health professionals engage with this increasingly popular but unproven practice?.” https://spiral.imperial.ac.uk/bi…

3. NCT02407184 – List Results – ClinicalTrials.gov