Why not give better sex education in schools in the first place? I would bet money on most children's sex education consisting of a video and a 5 minute talk from an embarrassed teacher.
In regards to pregnancies the formal education isnt an issue. I've worked in education for decades and all the students I have encountered who have got pregnant were fully aware of how it happened and what the repercussions of their acts would be. They didnt get pregnant because they didnt realise it would make them pregnant, they got pregnant because they wanted to. (generally speaking)