We inherit our microbiomes from our mother, picking up billions of them as we slide from her largely bacteria-free womb through her microbe-laden vagina. Being slathered in vaginal microbes might not seem like much of a treat but it’s vital for a newborn.
Babies end up with a very different portfolio of skin and gut bacteria depending on how they are delivered. Those who are born naturally harbour a more diverse array of bacteria, which resemble those in their mother’s vagina, including several species that are important for digestion. Those who are delivered by C-section are colonised by a less diverse array of bacteria, including some like Staphylococcus that are picked up from the hospital environment.
These early differences could directly affect a baby’s health for these first colonisers determine which the species that will follow. The bacterial heirlooms that babies inherit from their mothers might act as a shield, preventing more dangerous microbes like from setting up shop. By changing baby’s first bacteria, C-sections could alter the make-up of their later communities, leading to long-term effects on health and nutrition.