A baby's heart starts beating within just a few weeks of conception, that alone is enough to convince me that it's more than a blob of flesh. Abortion is also known to not always be 100% successful, sometimes the baby survives with serious injuries and even severed limbs.
The whole "it's their body, they can do with it what they want" argument doesn't make much sense to me because they're usually arguing with people who believe that it's a living baby, not just a fetus, therefore it's not just the mother's own body they're dealing with. Sometimes, yes, the process of birth may not go well and the mother can suffer some problems. But because of my conservitive views I'm inclined to believe that even if it was a situation of rape or whatever, it's better to go through with the birth process and a bit of pain than to risk being wrong about the baby being alive, and killing a child.
That's just my views. I'm not going to argue about it because online debates never seem to help anything or convince people of things contrary to their current views, so I'll just leave it at that.