What is "placentophagy"

n. (context rare English) The feeding on placenta

Placentophagy (from 'placenta' + Greek φαγειν, to eat; also referred to as placentophagia) is the act of mammals eating the placenta of their young after childbirth.

The placenta contains high levels of prostaglandin which stimulates involution (an inward curvature or penetration, or, a shrinking or return to a former size) of the uterus, in effect cleaning the uterus out. The placenta also contains small amounts of oxytocin which eases birth stress and causes the smooth muscles around the mammary cells to contract and eject milk. There have been very few studies that seek to prove that eating placenta provides these hormonal effects.

There is also a school of thought that holds that placentophagy naturally occurred to hide any trace of childbirth from predators in the wild. Most placental mammals participate in placentophagy, including herbivores; exceptions include Pinnipedia, Cetacea, camels and, in most cases, humans. Placentophagy has been observed in Insectivora, Rodentia, Chiroptera, Lagomorpha, Carnivora, Perissodactyla, Artiodactyla (with the camel as a noted exception), and Primates. Marsupials, which are an order of metatherian (pouched) mammals, resorb rather than deliver the placenta, and therefore cannot engage in placentophagia; they do, however, vigorously lick birth fluids as they are excreted.

Some research has shown that ingestion of the placenta can increase the pain threshold in pregnant rats. Rats that consumed the placenta experienced a modest amount of elevation of naturally-occurring opioid-mediated analgesia. Endogenous opioids, such as endorphin and dynorphin, are natural chemicals, related to the opium molecule, that are produced in the central nervous system. Production of these endogenous opioids is increased during the birthing process. They have the ability to raise the threshold of pain tolerance in the mother. When coupled with ingested placenta or amniotic fluid, the opioid effect on pain threshold is dramatically increased. Rats that were given meat instead of the placenta showed no increase in the pain threshold. There have been no scientific studies which show that placentophagy enhances analgesia in humans.