:Pro-choice implies that it should be the woman's choice, and is used by groups supportive of legalized abortion. Pro-life implies that aborting a fetus destroys a life, and is used by groups opposed to legalized abortion. The terms I use describe both groups, but aren't loaded since neither group uses them to describe themselves, among other reasons. Allow me to explain: 

 From the pro-life viewpoint, a woman's choice is less important than a baby's life, just as anybody's right to choose to murder somebody is less important than their right to live. On the same token, from a pro-choice viewpoint, a woman's right to choose to abort something that clearly isn't a life is more important than the government's right to tell her otherwise. 

 So, pro-abortion and anti-abortion only show whether you think abortion should or shouldn't be legal, and don't imply that the other side is anti-choice or anti-life. They're much more neutral and more accurate than pro-choice" and pro-life.