It's just for the child. Not for the irresponsible parents who made bad choices on both sides.
Unfortunately, you cannot change biology. Women can't give the right away to bear a child. You can't give a man your uterus to carry and care for. So scientific law here, trumps any law that man could write for it when it comes to the woman's body, and no two women may feel the same way about how that will or will not effect their body. But it is their body.
That's why I say that everyone, man and woman, should know what their potential partner would do in that situation if it should arise. Then you can choose not to go further. It's simple logic, and yet it's ignored by the general populous repeatedly.
In short, I think both parties should be liable.
Apparently, my views haven't changed on this in 5+ years. The only thing I would add now is an encoding system for the registry so religious nuts can't go around killing people who may have had an abortion, or target people in any way.
It's the fairest way possible for a populous that can't think before they procreate.