couple of comments, here:
While I agree that that is being careful, there is only one way to be 100% sure.
i can think of several.
I think what REALLY needs to happen is for society to do everything possible to make MEN take responsibility for the children they help conceive. For almost every child on welfare there is an able-bodied man who has shirked his responsibility as a father. The only women who should ever end up on welfare are those who have been widowed, or whose husband (boyfriend, whatever) has become disabled.
There should be a real sense of SHAME for any man who gets a woman pregnant and dumps her, or who abandons his wife and children.
not all women are easy to live with, and sometimes we marry them before we know this. having been a custodial dad, and now paying supoprt, i do beloieve in the system. having been more generous than the law requires, i am respected by my kids for doing what is right, even when their mother does not.
no man is saddled to a woman who is unreasonable. what is unreasonable? thats the only question worth arguing.