"Vaginal seeding," in which the mother's vaginal microflora is transferred onto a newborn delivered by cesarean section, may be exposing babies to the risk of further infection, said several pediatric and infectious disease specialists from the U.K.
Aubrey Cunnington, MD, of Imperial College in London, and colleagues, warned in The BMJ that while vaginal seeding is gaining popularity in multiple countries, there is no evidence that this procedure actually works.
In fact, transferring the mother's bacteria via a vaginal swab onto the baby's eyes, mouth, face and skin may have the potential to harm a newborn, they wrote in an editorial.
"There is now quite a lot of evidence that differences in the microbiome are associated with risk of developing conditions such as allergies and obesity. However people have made a leap of logic that gut bacteria must be the link between caesarean section and risk of these diseases," said Cunnington in a statement. "Doctors, nurses, midwives and parents need to be aware they are doing something with a potential risk that currently doesn't have any evidence of benefit."
As the researchers noted, previous studies have suggested differences in the microbiome of an infant born by vaginal delivery compared to one born by cesarean section. But the only ongoing clinical trial investigating vaginal seeding is focused only on the alteration of the neonatal microbiome and not any clinical outcome.
Specifically, Cunnington and colleagues mentioned the potential for transferring such diseases as group B streptococcus (the most common cause of neonatal sepsis), herpes simplex virus, Chlamydia trachomatis, and Neisseria gonorrhoeae. Certain countries, including the U.K. and Australia, do not test for these pathogens during pregnancy.
"One colleague had to intervene when a mother with genital herpes, who had undergone a caesarean section, was about to undertake this process. Swabbing would have potentially transferred the herpes virus to the baby," said Cunnington.
In fact, when treating infants with potential infections, the authors noted that it is important to ask if vaginal seeding was performed, as it may influence a clinician's assessment of the risk of serious complications.
Due to unclear evidence of benefit, they have advised their hospital staff not to perform vaginal seeding. They add that patients who wish to perform the process themselves should be informed of the theoretical risks, but that their autonomy should be respected. Instead of vaginal seeding, Cunnington and colleagues suggested that emphasis should be placed instead on encouragement of breastfeeding and avoiding unnecessary antibiotics.
While they do not rule out the potential benefits of vaginal seeding down the road, they noted that studying its effects may be difficult, as it will require large clinical trials with years of follow-up.
"It might seem reasonable to perform this simple and cheap procedure, even without clear evidence of benefit, but only if we can be sure that it is safe," they wrote.