Young wives' tale
But there has been a longstanding belief among some new mothers that eating the placenta can yield benefits.
One supposed reason is that it can reduce the incidence of post-natal depression. It has also been claimed to have nutritional properties needed by women after childbirth.
But consultant obstetrician Maggie Blott dismisses the post-natal depression theory. In fact, says Dr Blott, a spokeswoman for the Royal College of Obstetricians and Gynaecologists, there's no medical justification at all.
"Animals eat their placenta to get nutrition - but when people are already well-nourished, there is no benefit, there is no reason to do it," she says.