Researchers have found some indications that C-section babies are healthier (develop a more natural skin microbiome) if smeared with vaginal fluids from their moms after delivery. Which makes a lot of sense, once one thinks about it, but isn't the sort of thing one normally thinks about.
Birth of a microbiome: Researchers smear babies with vaginal fluid | Ars Technica
C-section newborns slathered with moms’ secretions may dodge lifelong health problems.