One of the main reasons for being pro-choice is the belief that people have the right to control their own body. Specifically, they cannot be legally compelled to donate their organs or bodily fluids to someone else, no matter how great the other person's need.
If someone is dying of kidney failure, and you are the only person whose tissue matches, no one can force you to donate a kidney.
If someone needs a bone marrow transplant, no one can force you to donate your bone marrow.
There is no legal requirement for anyone to give blood.
Therefore, no woman can be forced to give up her bodily autonomy just because a fetus would die if it was removed.
This basic human rights undercuts the very premise of "it's a human being." no one has the right to use someone else's body against their will. Any woman who chooses to remain pregnant, is generously donating the use of her body -- and that is not just her uterus, but her whole system -- to the needs of another creature. But under no circumstances is that creature legally entitled to demand that.
