Birth Mode-Related Differences in Gut Microbiota Colonization and Immune System Development

Background: The process of early gut colonization is extremely variable among individuals and is influenced by numerous factors. Among these, the mode of birth will strongly shape the early microbial exposure and immune environment of the neonate.

Summary: Here, I review how the concomitant processes of microbiota and immune system development are altered by C-section delivery and the effects of such alterations on long-term health. Key messages: C-section delivery impinges on microbiota and immune system development through various means: (i) if labor is lacking, intrauterine immune responses dependent on this process will not occur, affecting the immune environment of the neonate; (ii) the lack of exposure to the vaginal and fecal microbes of the mother will alter the type and diversity of the microbes that colonize the gut at birth; (iii) the different starting points in terms of microbial exposure and immune environment will mark the course of microbiota and immune system development during the first months of life, generating multiple feedbacks between these 2 processes. Given that the first months of life represent a crucial time window in the ontogenesis of the immune system and the establishment of tolerance, C-section delivery will impact on the lifelong risk of developing immune disease.