Women only go to Gov't Certified Doctors and that they are NEVER allowed private healthcare -- All office visits, all procedures, all drugs given must (to the one) be stored in an FBI database to ensure 100% Protection of all "possible" fetuses.
In fact to further ensure that no fetus goes undetected you should insiste women are tested twice monthly for pregnancy -- should check them for diseases that often too so we "know" the woman is providing a safe womb too.
You could trust that in a free-society the pre-born are very valuable AND they are not protected (as all markets, including self-defense operate in a state of perfect competition).
Protectionism for one group always (according to all world history) leads to the formation of other groups seeking perfect protection.
A free-society is built on 100% Anonymity and Privacy
*&^ Constitution --- Constitutional Rationality