I totally understand what you're saying CG, because I don't think I could get my head around terminating a baby I'd have to give birth to anyway, who could survive without me. It's just not something I could view as "ethical" and therefore not something I could do myself.
THAT ALL SAID though, another woman and her body and her pregnancy has nothing to do with me and my personal ethics.
For that reason, I think it really should be left up to the woman entirely. It is still her body that has to deal with it one way or the other. It's still her offspring that is developing in there. It is still relying on her for its survival, and if she doesn't want to give it that, then that is absolutely her right IMO.
I don't actually believe, however, that many women just go, "Oh, yeah, I've lasted 30 weeks into this pregnancy, but stuff this... I want a termination." I'd say that anyone who did that either didn't know they pregnant until that point, needs some counselling or has severe health issues which warrant a termination.
IF by some change a baby that was meant to be terminated makes it out alive, I do think that at THAT point, it has equal rights to the mother. A baby, born and not depending on another human being's body for survival any longer (though probably in need of medical care after that, I'd assume), deserves to have its life protected as any other baby born.
But UNTIL it's born and breathing, its rights should never trump that of a living, breathing, existing human.