Vaginal seeding is the practice of using cotton gauze or a cotton swab to transfer vaginal fluids to the mouth, nose or skin of a newborn. The purpose is to transfer a mother's vaginal bacteria to her baby. The American College of Obstetricians and Gynecologists currently doesn't recommend or encourage vaginal seeding outside of a research setting.
If a C-section is done before labor begins or before a woman's water breaks, the baby won't come into contact with maternal vaginal fluid or bacteria. The theory is that vaginal seeding will establish bacteria in the baby's gut that could reduce the risk of asthma, atopic conditions such as hay fever (allergic rhinitis) and eczema, and immune disorders.
However, the long-term benefits of vaginal seeding are unclear. In addition, there's concern that vaginal infections, such as group B streptococcus, herpes, chlamydia and gonorrhea, could be passed from mother to baby. Further research is needed.
In the meantime, if you want to promote your baby's gut health, consider breast-feeding. Bacteria present in breast milk and on the skin around the nipple have been shown to contribute to the seeding of the infant gut.