That's a good example, and a complicated one, because the anti-choice people figure that if you accept their argument at the stasis of definition ("the life was taken"), then the value question will decide itself.   That's not actually true, as some arguments in medical ethics literature have made clear.  (There was a famous argument about what happens if you wake up one morning and find yourself hooked up to someone else's life support.  You're told that you have to remain on the machine for nine months or the other person will die. The ethicist argues that this is untrue: because you didn't ask to be put on the machine, you are free to unhook yourself even if the act will result in the death of the other.)

But more to the point, we can go back to the conjecture question and ask, "What is actually happening?"  And we can see that event as the reduction of harm to the woman, as an assertion of her moral right to freedom, as a lot of other things that have nothing to do with the definitional status of the fetus, which is dubious at best and which should not be allowed to trump every other consideration.