There are plenty of things that can be done to discourage it, and to encourage and support kids who do smarter things. On many campuses, the administration is actively pushing promiscuity and making it tough for kids to avoid.
So right you are. AND-- so do many CHURCHES. In the mid '80's, several teenage girls got pregnant in my youth group.In public, at least, there was no shame attached to this. While I AGREE they should NOT have been made to wear an "A" on them, those of us, who wanted to remain pure, were the ones that were called "freaks, losers,, prudes,unrealistic, for the times", and so on, and CASTIGATED by much of the group, EVEN some of the leaders.
Remember-- that was roughly 20 years ago. I doubt things are any better, in that regard today. Teens who desire to lead true, faithful, Christian-based lives should be applauded, and pointed out as examples of virtue, NOT made fun of, and shunned, by those leading such peer groups.