So what if my kidneys fail and I need a kidney transplant to live. But the only compatible donors refuse to donate a kidney to me. I cannot make them. I have no right to something that is part of their body. But I'm going to die if I don't get their kidney.
The Pro-Life stance would be they must give me a kidney so that I may live. But the Pro-Life stance would lose in a court of law.
So an unborn child will die if the mother doesn't continue to provide life support until the fetus is viable. But, according to the principle of body autonomy, no one can tell that mother that she has to continue to provide life support.
The Pro-Life stance is that she must provide life support until the child is born. But today, the Pro-Life stance lost in the Supreme Court.