Placentophagy
A study shows that even when pregnant and pre-parturient female rabbits are presented with placental meal there is little participation in the behavior but all postpartum mothers ate the afterbirth.
When compared with the consumption of liver, another protein source, the occurrence of placentophagia alone increases by roughly 55% in the short 1–5 day period following parturition.
[8] Additional research has shown that ingestion of the placenta and amniotic fluid influences the pain tolerance in pregnant rats via elevation of naturally occurring opioid-mediated analgesia.
[4] Production of endogenous opioids produced by the central nervous system, is increased during the birthing process which raises the pain threshold of the mother.
A test whereby rats were given meat rather than placenta supported the contribution of the afterbirth components to the enhanced opioid effect by showing no increase in the pain threshold of the post-partum mother.
[4][5] There are numerous hypothesized benefits to the practice of placentophagy in both human and nonhuman mammals, which are seen as the direct motivation for various animals to engage in the consumption of the afterbirth.
[5] These hinged on the idea that prior to parturition mothers ceased to eat and so, immediately after birth they consumed the placenta to satisfy an intense hunger.
A further idea was that of specific hunger, according to which the maternal figure participated in placentophagy in order to replenish any resources depleted during pregnancy that were contained within the placenta.
[2][4][9] Another aspect of placentophagy that was initially considered a beneficial reason for its occurrence was that the consumption of the afterbirth ensured cleanliness of the nest and eliminated any sign of new and vulnerable offspring.
[2] A newer hypothesis about the maternal consumption of afterbirth in mammals is that the placenta contains compounds that increase pain tolerance post parturition.
[4][9] Although it is known that during pregnancy and labour there is a natural increase in internal production of enkephalins and endorphins that decrease the sensation of pain, studies indicated that the consumption of placenta by maternal rats after delivery spiked the subsequent numbers of these opioids.
[15] Most recently, the CDC[16] published a report of a newborn infected with group B Streptococcus (GBS) bacteria likely after the mother ingested placenta capsules.
