I'll try to summarize the issue with some cut-and-paste.
The bottom line about abortion is this. Do you trust women to make their own moral judgments? If you are anti-abortion, then no. You do not. You have an absolute moral position that you don't trust anyone to question, and therefore you think that abortion should be illegal. But the second you start making exceptions for rape or incest, you are indicating that your moral position is not absolute. That moral judgment is involved. And that right there is where I start to get angry and frustrated, because unless you have an absolute position that all human life ... [is] equally valuable ... , then there is no ground whatsoever for saying that there should be laws or limitations on abortion other than that you do not trust women. ...
If you're pro-choice, you have to give up the right to have a "say" in someone else's choice. If you're pro-feminist, you have to give up the right to expect your personal feelings to be more important than women's public rights--including the right to be unpleasant, if, in her judgement, unpleasantness is called for.
Translated into more practical terms: there can be no qualifications on a pro-choice position along the lines of 'I'm pro-choice, but restrictions on third trimester abortions are okay' or 'I'm pro-choice, but parental consent laws for minor women are okay' or 'I'm pro-choice, but outlawing dilation and extraction ("partial-birth abortion") is okay'. If you make these kinds of qualifications, this argument goes, you are not, in fact, pro-choice; and in particular, you do not respect the rights of women to make their own decisions about their bodies. It's a line of thought I recently came to on my own, reflecting on Kantian pro-choice arguments; and I defend this point of view in the comments.