The human body contains 10-100 times more microorganisms (mostly bacteria but also archaea, eukaryotes, and viruses) than it does its own human cells. This is referred to as the human microbiome. Most of the organisms of the human microbiome inhabit the intestines; they are also found in the nose, vagina, and on the skin.
The American College of Obstetrics and Gynecology notes (Reference 1 below) that in recent years the number of cesarean births has increased in the United States and most other industrialized countries. And so have the rates of allergic and autoimmune diseases. It's possible that these trends are linked because C-section newborns are not exposed to microorganisms in the vagina as vaginally delivered newborns are. Analysis of records of 2 million Danish children born between 1977 and 2012 showed that, compared to children delivered via C-section, those delivered vaginally had much less risk of asthma, arthritis, inflammatory bowel disease, and immune system problems (Reference 2 below).
These and similar findings have prompted interest among parents and health professionals to incorporate transfer of vaginal fluids to a C-section newborn in order to decrease the risk of developing these diseases (called vaginal seeding). This is accomplished by a birthing attendant obtaining some of the mother's vaginal fluids on a sterile gauze pad and swabbing the newborn's mouth, nose, and face with them.
Before vaginal seeding can become a regular form of obstetric practice, the method must be studied in greater detail to determine if it is both safe and effective. Carefully designed studies must determine which organisms in transfer fluids are most helpful and which, such as infectious viruses, could be harmful. The studies must also determine the conditions for optimal outcomes, for example, maternal sites for obtaining fluids, newborn sites for receiving fluids, and optimal times for transfer.
- American College of Obstetrics and Gynecology (2017). Vaginal Seeding.
- Haahr, t. et al. (2017). Vaginal seeding or vaginal microbial transfer from the mother to the Caesarean-born neonate: a commentary regarding clinical management. British Journal of Obstetrics and Gynecology, 125, 533-536. (https://obgyn.onlinelibrary.wiley.com/doi/abs/10.1111/1471-0528.14792).