Well, the baby is still a part of the mother when an abortion occurs. They aren't seperate people yet. So, its the mothers choice if she should abort the gestation process, drink alcohol, or raise a perfectly healthy baby.
It might not always the best choice since having children is a mitzvah - but the woman still has a right to choose what her fate might be before it has any serious implication on the life of a future child. Plus, its ethically wrong to deny somebody the right to their own freedom when dealing with largely personal issues.
So, the whole shabang boils down to how you classify pregnancy. Is the fetus a person yet? I really don't think so. But some people do. It's a shame we can't even agree on something as simple as that.
-Elbaz