Breech birth

"Those at whose birth the feet appeared first, instead of the head, which is considered the most difficult and dangerous form of parturition, are called Agrippae, a word formed from aegritudo, or "difficulty," and pedes (feet). But Varro says that the position of children in the womb is with the head lowest and the feet raised up, not according to the nature of a man, but of a tree. For he likens the branches of a tree to the feet and legs, and the stock and trunk to the head. "Accordingly," says he, "when they chanced to be turned upon their feet in an unnatural position, since their arms are usually extended they are wont to be held back, and then women give birth with greater difficulty. For the purpose of averting this danger altars were set up at Rome to the two Carmentes, of whom one was called Postverta, the other Prorsa, named from natural and unnatural births, and their power over them.""