If the fetus is viable, it should have autonomy. However, we cannot force the woman to carry it one second longer than she want to. Ergo, the only ethical choice is to extract the child and stick it in a hot box.
Actually, viability is not that viable. Fetal brains see most of their development in the last trimester. It is really bad for the fetus to be removed at viability. Just because you can't force the woman to carry the fetus is not a good reason for your ethical choice. The ethical choice is to tell women something like this:
Look, you have the right to abortion for the first, say, 22-24 weeks without anybody getting
involved but the doctor you select. But abortion is many times safer than childbirth in the first
12 weeks, and not as many times safer as the weeks increase. So you should see viability as a
kind of limit on why you want an abortion.
The future child would not get good brain development outside the womb, so you waited way
too long to have an abortion for any reason except a life or death or major health crisis.
If you were prevented from getting an abortion by a rapist who held you captive or are carrying
a fetal anomaly just discovered or something, you may want an exception and some doctors would
probably agree, and the state should really not have a say.
But if you wait too long, no doctor wants to perform an abortion except in case of a real disaster,
so don't wait that long, or if you do, continue the pregnancy to let the fetal brain develop adequately.