I know the story you are referring to. He didn't say he did the abortion, but he knew of it, and was using it as an example of why he would not sign a parental consent law (he claimed the girl had been raped by her father).
The story, in its whole, was fake, and there was no such girl, period. He regretted the "misunderstanding" and blamed somone else. One of his staffers spun it as being a gaffe equal to when Bush's father made statements about a girl that had something like 12 abortions (also untrue).