Intended for healthcare professionals


“Vaginal seeding” of infants born by caesarean section

BMJ 2016; 352 doi: (Published 23 February 2016) Cite this as: BMJ 2016;352:i227

Author's Reply to Butler

Butler makes several criticisms of our recent editorial article (1) on the role of health professionals in vaginal seeding.

Butler suggests that we ignored “huge piles [of] medical literature” which describe the necessity of the transfer of vaginal microbiota for the development of the newborn immune system. Unfortunately none of this literature is cited to support this statement. We acknowledge that the interaction between the microbiota and immune system is a fascinating and rapidly evolving field of research, and in our editorial we cited a review article on this topic (2). However, when we wrote our editorial we were unable to identify any published studies showing that the transfer of vaginal microbiota to newborn infants born by C-section produces any change in the development of the immune system. Shortly before our editorial was published, a small study was published in Nature Medicine, which showed that vaginal seeding can make the neonatal microbiota more similar to that of a vaginally born baby (3). This study did not examine any immunological parameters. Carefully controlled experiments in laboratory mice have been very important for demonstrating proof-of-principle that the microbiota can influence development of the immune system, but do not necessarily predict what will happen in humans exposed to much more complex external influences. It would be interesting if future clinical trials of vaginal seeding examine its influence on the development of the human immune system.

A second criticism seems to be that we neglected to consider the acquisition of nosocomial bacteria. This was certainly beyond the scope of the editorial. Again it would be a very interesting question for a clinical trial to examine whether vaginal seeding offers any protection from acquisition of nosocomial pathogens, and whether there is any trade-off with acquisition of antimicrobial resistant pathogens which may be carried by the mother.

Finally, we are criticized for not being “on board” with what has “served humanity well in the past” ie. natural vaginal birth. At no point in our article do we state or imply that C-section would be a generally preferred mode of delivery to vaginal delivery. In fact our concern about vaginal seeding is much more subtle than Butler implies. We are concerned that there may be a risk of neonatal infection following vaginal seeding, although the magnitude of this risk remains to be quantified. We believe that health professionals should not feel obliged to perform a procedure which may carry risk and does not have an established benefit. We acknowledge that parents may wish to perform the procedure themselves, and recommend that they should be allowed to do this if they understand the potential risk. Having cared for many infants with severe Group B Streptococcus and Herpes Simplex Virus infections, some of whom have died or been left with serious disabilities, we would not want any more infants to suffer the same fate because we had not warned about the potential for transfer of these pathogens by vaginal seeding. Unfortunately being born and giving birth are two of the most dangerous life events and infections account for a large proportion of neonatal deaths globally (4). Access to timely and better healthcare is one of the reasons why neonatal mortality is low in many well-resourced countries, and lack of access is one of the reasons why it is so dreadfully high in many resource-poor settings. Appropriate medical intervention in the process of childbirth undoubtedly saves lives, but we do need to ensure that interventions are genuinely appropriate. The only way to do this is by performing high quality clinical trials, and this is what is needed to establish the safety and effectiveness of vaginal seeding.

1. Cunnington A J, Sim K, Deierl A, Kroll JS, B Eimear, Darby J. “Vaginal seeding” of infants born by caesarean section BMJ 2016; 352 :i227
2. Maynard CL, Elson CO, Hatton RD, et al. Reciprocal interactions of the intestinal microbiota and immune system. Nature 2012; 489:231-41.
3. Dominguez-Bello MG, De Jesus-Laboy KM, Shen N, Cox LM, Amir A, Gonzalez A et al. Partial restoration of the microbiota of Caesarian-born infants via vaginal microbial transfer. Nat Med, 2016. doi: 10.1038/nm.4039.
4. Lawn JE, Blencowe H, Oza S, You D, Lee ACC, Waiswa P, et al. Every Newborn: progress, priorities, and potential beyond survival. Lancet 2014; 384: 189-205.

Competing interests: No competing interests

07 April 2016
Aubrey Cunnington
Clinical Senior Lecturer in Paediatric Infectious Diseases
Imperial College
Medical School Building, Imperial College, Norfolk Place, London