How is this not cannibalism?

Liz Klimas' post on January Jones the Placenta Eater got me thinking.

This trend of consuming one's own "after-birth" is really gross -- and not only in the whole "that's-super-nasty" way," but also in the "isn't-that-cannibalism?" sort of way.

Before you discount eating placenta as akin to eating a booger, consider that it's not simply a secretion or compound that the body creates and then vacuates.

According to the Merriam-Webster Dictionary, "placenta" is something more:

1: the vascular organ in mammals except monotremes and marsupials that unites the fetus to the maternal uterus and mediates its metabolic exchanges through a more or less intimate association of uterine mucosal with chorionic and usually allantoic tissues;

So, if a human is consuming a human organ, isn't this cannibalism?