Dysbiosis in the Neonatal Period: Role of Cesarean Section.

From epidemiological studies and studies done evaluating microbiomes in infants, there is a strong signal that the infants born by elective cesarean section (C-section) develop microbiota that differs from those babies born by vaginal delivery. Epidemiological studies show increased odds ratios for the development of immunological disorders such as type 1 diabetes, celiac disease, asthma, allergic diseases as well as metabolic diseases such as obesity in babies born by C-section. These are interesting associations, and if supported by additional studies that rigorously control for confounding factors, they will have major public health implications. Such studies represent major challenges because the confounding factors are numerous. The fact that provision of vaginal bacteria to C-section-delivered babies using a mouth swab that may actually transmit these bacteria to the infant is of interest and supports the concept that this can be done to alter the infant microbiota. However, significant caution needs to be taken, and alternative approaches that are safe as well as effective need to be considered; follow-up studies showing efficacy as well as safety need to be evaluated in the long term.