Here's what I think it boils down to:
Does banning abortion lead to fewer abortions?
But the problem is we can't possibly know the answer because a backstreet abortion is just that.
Does it deter irresponsible sex? It may do this, but we'd need research, which is too easily manipulated and can never be accurate anyway.
If it did deter irresponsible sex I'd say maybe that's an argument to make abortion illegal, but then you'd have to offset it against the suffering of children being removed from parents who never wanted them, going into care, fostering etc. etc.
And I don't think you'd end up with less overall suffering.
So I'm pro-legal abortion.
If you decide at 22 weeks you just can't do it and want the baby dead? I don't believe you should be allowed, I think you should have to give them up for adoption at that point. I'd be interested to know often a case such as that occurs though, I'd hope rarely.