When you’re a teen, the spirit (well-intentioned as it might be) is weak and the flesh is willing.
I suspect the best way to cut back on teenage sex is for kids to be better supervised by adults. When you have lots of free time and ample opportunity, you are much more likely to engage in things like sex (and drugs for that matter).
They should give all the kids saltpeter (or Lexapro). It’ll prevent all those special elections.