I do have autonomy over my body—to a point. Suppose I visit a friend who is a mother of an infant. If I take into my arms that infant, then I have an obligation to protect that infant until I can get it into a place of safety. I do not have the right to just drop it to the floor should I decide I no longer wish that burden I voluntarily took up. The law holds me responsible. I see little difference in pregnancy. There’s more inconvenience but, as far as I am concerned, the obligation is the same.
A fetus, after being implanted in the uterus, has to have its immune system functional to defend the onslaught brought against it by the mother’s immune system.
This simple fact alone is empirical evidence that the child growing within is NOT the woman’s body - it is totally different human being.
They have no excuse.