Granted, they are speaking of cats, but listen to what they stated on the show ‘In the Womb:Cats’ regarding the mother’s ingestion of the placenta.
“Instinctively, the mother eats the placenta, which contains high levels of oxytocin. As this powerful hormone surges through the mother’s blood, it helps her produce milk, but its effects are more than just physical, it has a strong psychological impact. In all mammals, oxytocin stimulates feelings of trust and affection, and it helps the mother bond with her offspring. Without the extra dose, she might reject them.”
I am not trying to say here that if a human mother does not ingest her placenta that she will reject her baby, but its good to know that scientists are acknowledging more and more not only the physical effects of a mother ingesting her placenta, but also the psychological effects. Thanks Nat Geo!