The woman has bodily autonomy. The fetus doesn't somehow get special rights that we don't afford to living, breathing people, to use the women's body against her will. People often don't choose to get pregnant, or don't choose to stay pregnant. That's their right, IMO. We extend that right to not saving living, breathing people. What justification for special rights to zygotes, fetuses, or viable fetuses, none of which have ever had any real interaction with society, have never had friends, aspirations, etc.?