The practice of eating placentas was also fashionable in the 1970s among so-called "earth mothers", but its popularity has since declined, with few mothers wanting to take their placentas home from hospital with them!
Indeed it is commonplace for some cultures and, of course, many of our friends in the animal kingdom have always enjoyed it. However, to your average discerning human being it still doesn't seem that appealing a prospect. In the Western world it is accepted, although unproven, that eating placenta will reduce the risk of post-natal depression. This is because the organ is rich in minerals and vitamins, particularly B6, which can help to fight depression.