I have just come to the realization that Sangha is merely a "contrarian." He simply "asserts" something and thus it becomes a "proven fact." He simply states the opposite of your position and this becomes a "proven fact."
I suppose it is possible that if he has had very few heterosexual experiences and remained in constant visual contact with all of the women he did have such experiences with he could state with some certainty he has never gotten anyone pregnant. It's also possible if he has always been celibate, or has never been interested in sex with a woman.
He can also state that if a man stays in constant visual contact with a woman from conception until birth, eventually he will notice changes in her body indicative of pregnancy.
What he cannot state with such absolute certainty is that ALL men do so, and that those who don't WILL KNOW when a woman they have slept with has gotten pregnant, had and abortion, or had the baby.
He also keeps focusing on the issue of child support, which is only one of the many concerns with having an unwanted child. In any case he will simply make absolute statements contradicting whatever is said, and then "accept your surrender" when you get tired of responding.