placentophagy
Comparative zoology Most placental mammals, including herbivores, have eaten their own placentas, including Insectivora, Rodentia, Chiroptera, Lagomorpha, Carnivora, Perissodactyla, Artiodactyla, and Primates.
The benefit is attributed to a poorly characterised substance called Placental Opioid-Enhancing Factor (POEF), which is allegedly found in placenta and amniotic fluid and said to modifiy endogenous opioid activity, and reduce post-partum pain
Ethnomedicine The practice of eating the placenta post delivery. While it is not a common practice, a fringe group of advocates claim it reduces post-partum depression and improves nutrition.