The phrase "your rapist's baby" is linguistically a bit like "the time traveler's wife": The wife is not a person; she is chattel belonging to the (male) time traveler. Likewise with this hypothetical baby: It has no identity of its own.
That we believe we can justly inflict capital punishment on a rapist's child is also interesting.
You know, there was once another Supreme Court case where individual rights (namely, property rights) came into conflict with (controversial) claims of personhood: Dred Scott.
You could say I'm trolling here, because the truth is I do not vote on the basis of abortion issues, and, when push comes to shove, I would tend to allow it. So I am not, politically, quite the person you might think I am.
Nevertheless, it does make me extremely, morally, uncomfortable; it's something I wouldn't want to be mixed up in; and I can absolutely understand the philosophical arguments against it. Which is why I am able to make analogies like those above.
If you stop and think about it, Republicans' opposition to abortion, perversely, demonstrates that at least in some areas they have moral principles (though you might disagree with them) -- that they do what they believe is right, even when it's not in their interest. Because the people most disproportionately impacted by restrictive abortion rules are women of color. If Republicans were ruthless consequentialists, this is exactly the person whose abortion rights they would not want to restrict. So in a perverse way it tells me that (some of them) actually believe something.