Evolved birth physiology meets modern birth practice: Sustained effects of planned cesarean delivery on child hair cortisol in Brazil

Proceedings of the National Academy of Sciences, Volume 122, Issue 50, December 2025. SignificanceDuring labor, babies are exposed to mechanical forces and hormones that help prepare them for life outside the womb. Using data from a large sample of 4 to 7 y old children from Brazil, we found that those born by planned cesarean section had …