We as a society believe in bodily autonomy. If you can't force a corpse to surrender its organs because, while alive, the person who inhabited the corpse did not register as an organ donor, then you cannot force a loving, breathing human to house another human for nine months and then go through delivery, both of which are some of the most dangerous activities humans engage in. In addition, by 20 weeks, most pregnancies are wanted. Abortions are performed at the request of people who are grieving not becoming parents. This is helping no one.