It does matter. But the moment she had sex, her body is not being used against her will.
It is more like: Use a certain argument you don't agree with and see what happens!
I use it in some posts, while in others i clearly point out its flaw.
What i disagree with is when it was said that the choice to have sex automatically makes the men responsible for the child that may be born as a result of this act. I disagree with this, more than anything else, because if the sex binds the man, it must, unless we apply a double standard, bind the woman to the obligation of supporting her child. And if a woman resorts to an abortion, she is doing the opposite of what it means to 'support her child'.
I would say that what binds a man/woman to this responsibility is the existence of a person, who shares half of his/her DNA, and that is in need of support.