You already know that in an abortion, no one is typically killing the fetus (which btw is less of a human than a chicken egg is human), they're just removing it from the body it's parasiting off of. Not the mother's fault it can't survive, and I'm pretty sure you're for curing cancer or tape worm which also contain more human dna than a fetus does.
Besides, in many cases the fetus is already dead or terminal anyway.
And even if this was codified under law as murder, it wouldn't be the mother doing it, but a licensed professional, much like police, soldiers or wardens.
Thats's a lot of mental gymnastics to insert yourself into someone's health care and sex life. That's kind of weird...