The fetus should only be protected when they can survive outside the womb? What about the brain and sentience? It's okay to rip a fetus apart in the womb when they are sentient?
I think it's the best constitutional compromise between respecting the autonomy between the autonomy of the person with the uterus gestating, and the autonomy of the fetus. Roe vs Wade is by far the most ethical position in consideration of all.