Vaginal seeding is a novel procedure whereby vaginal fluids (and hence vaginal microbes) are applied to a new-born delivered by caesarean section, in order to create an equivalent biome to a baby delivered vaginally.
The motivation is that some research has linked deliver by caesarean section to a higher rate of asthma, overweight and other autoimmune conditions. Additionally it has been demonstrated that the process can partially reduce the difference between the biomes of babies delivered by different methods.
Vaginal fluids can host a wide variety of pathogens, and therefore there is a risk of causing infection by using this procedure. A BMJ editorial concluded that "the small risk of harm cannot be justified without evidence of benefit."
References
Vaginal seeding Wikipedia(Text) CC BY-SA