I know there's a faction that thinks that any exception makes one "pro-abortion".
The entire basis for the anti-abortion movement is the idea (with which I disagree, for both spiritual and scientific reasons) that 'life begins at conception' and therefore an abortion is 'murder.' Exceptions for rape or incest are tantamount to legitimizing murder of persons conceived in this way. What's 'pro-life' about that?
There really isn't any way to reconcile these things. Either killing ANY embryo or fetus is murder, or it isn't. Since I don't believe that 'life begins at conception' (an aside, in case anyone asks - the primary reason I don't believe this is that bazillions of 'conceived' embryos never implant and become full blown pregnancies, and I have a hard time believing that all of those conceptions that we never even knew about are dead persons invested with souls), I can't accept the 'murder' rationale for all abortions. If I did, however, I simply cannot see how one can argue for 'exceptions' based upon the manner of conception.