"In an unprecedented study led by Anita Kozyrskyj of the University of Alberta, it was shown that babies born by cesarean are deficient in a specific group of bacteria found in babies born vaginally. This gut bacteria is important for newborns, as it helps them digest food, regulate bowels, develop their immune systems, and protect against infection.
It's literally a one-time shot for a baby to get exposed to his or her mother's microbes — and it can only happen during a vaginal birth. Cesareans, it would seem, deny them that opportunity."
Are Women Having Too Many C-Sections in the United States?