In virtually all circumstances, with the appropriate caveat that I'd say that a late-term baby should probably be protected (but that this should be defined by some appropriate biochemical marker).
A baby that is not wanted is an organism that has effectively invaded the mother's body and is taking nutrients and putting her at risk. It is a parasite. Like all organisms, it has certain rights, but it has no right to take up residence in the body of another living creature.
This approach balances the autonomy of the woman with the rights of the baby. My approach would even make it so that any forced abortion or destruction of embryos would be treated as a crime against life not property. An intentional forced abortion in my mind should be treated as murder.