Accepting that a woman, who was raped and has complications with her pregnancy that would mean that she would die if there was no abortion, is a long way from accepting that every pregnant woman in a late stage pregnancy can just decide to have an abortion.
When you start talking rationally about the shade of gray of different laws it also becomes easier to have a rational discourse about the extremes.
One exemption to anti-abortion views I've seen expressed almost universally among pro-lifers is that abortion is okay if the mother's life is at risk(because at that point, abortion isn't murder, any more than an operation that kills one Siamese twin to save the other is). A lot of people try to start blocking out other exemptions for semi-random reasons, mostly because of the hemisphere fallacy, but the arguments are usually the sort of incoherent nonsense you only hear from politicians.
As Multiheaded added, "Personal is Political" stuff like gender relations, etc also may belong here.