It's their choice. Not mine, not anyone elses. Just like it's my choice, not your's or anyone else's, to drive drunk or steal or rape or murder.
The women aren't the only ones concerned, the living beings they're killing are involved too. And to anyone who claims otherwise, what exactly do you think a fetus is? Is it a rock? A flower? Is it the mother? The father? Or is it another being, but one that doesn't matter because it's "just a clump of cells"? That one's my favorite rationalization: "it's just a clump of cells". What the hell do you think you are, golden magic fairy essence?
Or maybe it's just that it's OK to kill something not fully formed yet. So maybe we should make a sliding scale of punishment depending on how old the victim is. Infants aren't full adults, killing them can get you a fine. Knocking off middle-schoolers will get you a few years of jail time. Retards, of course, are always in season. They can't think, why do they deserve rights?
Scientifically, the life of a separate organism begins at conception. This has nothing to do with religion or morality. At the point of conception, cells cease being components of their parents, and take on new and individual characteristics. So the question of abortion is not "whether or not it's killing someone", but rather "is the killing of this person justified?" If abortion advocates would simply admit this fact of science and move onwards from there, advancing reasons why murder in such cases should be legal, I probably wouldn't hate them as much.