Should there also be a mandatory education on pregnancy and its challenges taught to school-age kids?
Schools are very good at teaching the how-to of sex, but they don't do a thing about teaching the advantages of a stable relationship, or how to raise children, or anything else that comes AFTER the sex.
"This is how to have a baby... and this is how to protect yourself if you don't want one." Contraceptives don't always work... what happens then? Help once it's happened is difficult: a scared teenager who's just found out his girlfriend is pregnant isn't going to be thinking rationally, he's going to be thinking of all the bad things he's been taught, by the schools, that having a baby is going to cause for him. Is it any wonder there's that many single mothers?
I say teach about the advantages of sticking with their girl/guy. Instead of focusing on the negative aspects of sex, and trying to scare them away from it, teach them how sex is a good thing, children are great, and not buggering off after either one is even better.

I'd also like to note that I went to a Christian school (Private) and we were taught a whole lot about sex. What Moral Organisations are you talking about that are trying to remove it from schools?