Well if you want to talk about legal defenitions: I present to you Murder vs Manslaugther. In both cases, you have someone, who killed another person. Still we have 2 defintions depending of the situation with different sentences. So it would be completly fine(for lawcases) to regard the wishes of the would be mother as a factor for the type of crime commited by the man. Therefore you should not try to transfer something so flexible as the law to moral discussions.
I personally am fed up with the whole "is a unborn child at a certian point a human with the right to life" question. Not because I don't believe in the human right to live(which I do), but because life can be a burden especially nowdays and we shouldn't commit people to suffering(parents and their childreen alike), if the women doesn't believe she could be a providing mother or would psychology suffer from being forced to motherhood.
So you may cling to this fundamental question or try to accept that we should every person give the freedom to live their lifes as they see fit, instead of disregarding their free will for whatever reason. I hope you see where I'm coming from.