Abstinence is a dumb policy. It used to be, not too long ago, that once the age of 13-14 was reached, Marriage was an option. The reason for that was pretty simple, it was recognized that that was the age when people began to gravitate towards sexual activity. In order to keep the various Moral Codes, there was no option but to allow Marriage to occur.
Somewhere along the line people decided to push Marriage to a later age. However, the Moral Codes remained the same. The end result is that there is a certain portion(>50%) of the population who simply end up breaking those codes. No amount of Education is going to change that.
So we have basically 2 choices:
1) Lower the age for Marriage
2) Change the Moral Code
I disagree with 1. The ages were increased for good reasons, things like Education became very important. Too important to have Marriage, Kids, Jobs distracting large portions of the population.
I agree with 2. Our Education time/money is better spent teaching good choices and taking proper precautions in order to avoid unexpected Pregnancy and/or disease.