Figure 1.

Perinatal microbial encounters. Three windows of influential microbial encounters may be distinguished in the pre- and post-natal period. Maternal microbes as well as their metabolites may influence the uterine environment in which the fetus develops. Delivery mode shapes the initial microbial inoculum of the newborn while nutrition drives microbial composition during the postnatal period. Microbial imbalance during these periods alter susceptibility to pathogens and inflammatory disease in early and later life.