@ScarletFlygon: That's because for most people - doesn't matter if they're still in high school or they're in college or they're living in the real world at the age of 40 - sex has two sides: the loving side that you want to have with someone who you care about and have it as a loving, intimate moment, and the side where you just want to satisfy your sexual desire to get some.
While there are a ton of teenagers who have sex just to satisfy a desire, there are just as many doing it out of love, and there are just as many adults doing it for both of the reasons. The point is, some people (doesn't matter how old they are) have sex because it feels good. Just because someone's in high school doesn't mean they're any less mature mentally than a fully grown adult. You don't magically become any more mature after you become 18 or graduate high school. And just because some have sex just because it feels good and to satisfy a sexual desire doesn't mean that they magically don't know the risks (a lot more than the pregnancy outcome that you're concerned about) of it if they were taught it.