An organ is a component of a body. A baby is an entire human life form. You can't take an organ out of a body and have it grow up to be a poet or an astronaut.
If a baby in the womb is simply "a woman's body," what about the 50% of genetic material from the father?
I think the Republican Party's pro-life position to be discriminatory against women.
How is it discriminatory against women? Women are the only sex that gestate. Opponents of abortion simply feel that much abortion is highly questionable ethically and feel that a society's treatment of the weakest and most defenseless among them speaks much about the character of their society. If men gestated they'd feel the same way.
In modern society women do have complete autonomous control over their bodies in determining whether or not to become pregnant.