Also, it is expected that you eat the placenta after a baby is born in some religions
The placenta is highly nutritious, as it's intended, since it is the "food-store" for a baby in the womb.
Since the placenta is expelled during after-birth, it's common in numerous societies, mostly those we would consider less culturally advanced, to cook and eat it. It's more a cultural thing than a religious thing.
A large number of animals eat their placentas following birth. It's almost a requirement for them to live.
Cats are quite notorious for eating their own placentas following birthing, since it restores some of the energy they used in actually giving birth.
They even go so far as to lick clean the embryonic mucus from their young, partly to clean them for obvious reasons, but also to consume the nutritious gunk on the young that has come from the placenta.
And it's not uncommon in some reptilian and aviary species for the albumen, which surrounds the foetus in the egg, to be eaten immediately by the young, as it provides the same role as a placenta, and these animals require nutrition immediately, since unlike mammals, their parents do not provide them with milk.
