Nice.
I think in this case, making the choice to be on the medication is where your choice comes into play.
Once you make the choice to be engaged in fetus endangering activities, you have made the choice not to become pregnant, or not to gestate.
If you do get pregnant, though, and for some reason decide to have the baby, they can't force you to abort, I'm pretty sure that would be against the law.
Although a dumb decision in the first place.