It's odd that breastfeeding wasn't mentioned at all. We know how important colostrum is to setting up the infant gut! We also know that for breastfeeding to really do everything it should, there should be nothing but breastfmilk given by mouth until it's time for solids (sometime around six months, but it will vary by child). Exclusive breastfeeding is quite important in shaping the infant microbiome. Evidence is growing that a vaginal birth is important, too. Babies are supposed to have exposure to the vaginal bacteria on the way out. Some research shows it would be beneficial to swab the birth canal with a piece of gauze and then swipe the infant's face just after birth. I knew nothing about that 30 years ago when I gave birth to one of my children by cesarean, but I'm glad that I did nurse exclusively.