In some countries like the United Kingdom and the United States, a practice among parents has become fashionable in recent months in which those who have just had a child via Caesarean section swab their newborn with the mother’s vaginal fluids. This is known as ‘vaginal seeding’.

The aim of this practice is to try and restore the normal colonisation of their child’s microbiota. Several studies have shown that children who are delivered vaginally develop a similar microbiota to their mother, while those born via C-section have a microbiota made up of skin-based bacteria and even those present in the operating theatre. Furthermore, Caesarean procedures are associated with an increased risk of developing conditions like allergies and asthma.

In this respect, just a few weeks ago, researchers María Gloria Domínguez-Bello and José Clemente from the NYU School of Medicine and the Icahn School of Medicine at Mount Sinai, respectively, published a new study in Nature Medicine in which they showed that they could modify the microbiota of babies born via C-section by exposing them to vaginal fluids.

To do this, minutes after delivery they swabbed the newborns’ faces with a gauze impregnated with the mother’s vaginal fluid (the swab had been placed in the woman’s vagina hours before delivery). By analysing the microbiota present in the babies’ faeces 30 days later, they observed that they had a richer and more diverse microbiota, similar to that of babies delivered vaginally.

In spite of these positive results, the study’s authors are cautious. “It is still early to start implementing this technique in hospitals. Longitudinal studies are required,” explained José Clemente to Gut Microbiota for Health. “Our study looks at basic science, which we carried out in a clinical environment where we controlled a series of risk factors. For example, we ensured that the mothers did not have any pathogenic microorganisms in their vaginas, in order to avoid passing them on to their babies.”

This issue – ensuring that pathogenic bacteria like group B Streptococcus (that may even lead to a baby’s death) or the microorganisms that cause gonorrhoea, chlamydia or genital herpes, are not passed on – is the main concern for some experts, who warn that the solution may be worse than the problem and that uncontrolled vaginal seeding may lead to infections in newborns.

“Evidence showing this practice to be beneficial has yet to be presented and it poses a risk to the baby,” warned three neonatal specialists some weeks ago in the British Medical Journal, led by Aubrey Cunnington, who researches into infectious diseases at Imperial College London.

Clemente shares this view and urges caution, reminding us that “it is important that people understand they shouldn’t do this [vaginal seeding] alone because they are exposing babies to possible dangers. If someone is interested in vaginal swabbing, they can contact us and we can provide them with more information or perhaps even add them to our study.”

In spite of the scientific precautions, as Cunnington and his colleagues pointed out in their BMJ article, if parents decide to apply this technique to their babies, “we should ensure they are well informed about the possible risks.” And they recommend that until more scientific evidence is provided regarding the benefits of vaginal swabbing for babies, mothers should opt to breastfeed and avoid unnecessary antibiotic use. These two things, they said, can make a greater contribution to establishing a healthy microbiota in a baby’s gut than swabbing it with vaginal fluid.



Cunnington Aubrey J, Sim Kathleen, Deierl Aniko, Kroll J Simon, Brannigan Eimear, Darby Jonathan et al. “Vaginal seeding” of infants born by caesarean section BMJ 2016; 352 :i227

Dominguez-Bello MG, et al. (2016) Partial restoration of the microbiota of cesarean-born infants via vaginal microbial transfer. Nature Medicine 22, 250–253 doi: 10.1038/nm.4039