The bearing blog (a pretty cool blog I found a while back--an engineer turned SAHM and homeschooler writes about whatever takes her fancy) has a post with a couple of questions about sex ed programs that "work". Just a taste: "It isn’t self-evident that the programs that best reduce teenage pregnancy are the same programs that best reduce STI rates..."
Just a quibble on my part--and it would be a quibble with nearly everyone who discusses this subject, not just with bearing blog--but teenage pregnancy is not necessarily a problem. Unmarried teen pregnancy is a problem. Teenagers used to get pregnant all the time; the difference was that they got married--either before pregnancy or, hastily, after a pregnancy but before the birth*. At least one of my grandmothers married in her early teens (first baby arrived one year and one day later) and went on to have a long, apparently happy marriage. Go back far enough and we all have teenaged mothers and fathers in our family tree.
Of course, many people would argue that teenagers shouldn't get married, because they're too young or because it's hard for people who haven't been to college to support a family. To the first I say "bollocks". As to the latter, I think there's something wrong with a society that makes it so difficult for a young man to support a wife and child. But it's only hard, not impossible, especially if the couple have the support of their extended family.
*Cute story: My mother reports that her grandmother told her that, "When a couple get married, their first baby can come at any time, but after that it always takes nine months." This was coming from an elderly, Victorian-era woman in the 1950s, in the backwoods of "socially conservative" Mississippi, in a family with multiple Baptist ministers. Hasty marriages have been around for a while.