There are several medical reasons for abortion, which more or less fall under two categories: conditions that are a risk for the mother, and genetic conditions of the child that have a near 100% mortality. The vast majority fall under the latter heading. Most parents do not want to bear a child with a misery-inducing disease that will kill the baby 2 months later (e.g Tay Sachs disease). As for risks to the mother, I'm not too sure (I'm not a gynecologist), but an ectopic pregnancy (one outside of the uterus) is destroyed during the procedure, although whether or not it was viable in the first place is highly questionable.
Then there are the myriad of social reasons (rape, incest, financial burden) that are probably more common reasons for VTOP, although that may just be my misconception (pun intended).
But Sanaz is correct; pro-choice and pro-abortion are different. I just gave you some justifications for why abortion may be necessary, which from what I gather is what you need.
