I can't see how being dependant on someone else is a necessary criterion for being a human. After all, following birth we are all totally dependant on others to survive and to continue developing. And I cannot see how "developing" can be seen as a biased word, whether in regard to an embryo, a foetus or a baby. It' s all part of the same process - and of course it can go wrong at any stage, there is no guarantee of surviving, even after birth.