I'm familiar with the argument that an innocent baby shouldn't suffer because of the crime of another. That said there always comes a point when the discussion turns into a clash of opinions, with current legal opinions largely being that the fetus doesn't count as a human. It's good to have rational arguments to offer, particularly to people who don't particularly want an abortion but feel like there's no other way out.
As far as rape is concerned it seems like the kind of issue where it's easy to make proclamations as to what the unwitting and unwilling mother-to-be should do, from a safe space of being a man who can never find himself facing such a decision. Even setting aside the financial costs of dealing with a pregnancy and giving birth the physiological changes leading up to the birth, the potential for post-natal depression etc, not to mention to potential for emotional issues following a decision to give up the child for adoption, it provides lots of handy ammunition for those wanting to make a case along the lines of "why should the woman suffer all this on top of the trauma of being raped?"
I find the notion of abortion to be morally unacceptable and yet, if I'm honest, if my wife had ever been raped and ended up pregnant, I don't know how I'd have handled the thought of raising a child knowing that every time it called me "daddy" it would remind me of what had happened. And of course that's coming from a position when it hadn't happened to me directly, and living in a country where you don't get a bill for north of $10,000 just because you went into hospital to give birth.