As seen on TV: Teen sex

The Washington Post summary says it best:

Teenagers who watch a lot of television featuring flirting, necking, discussion of sex and sex scenes are much more likely than their peers to get pregnant or get a partner pregnant, according to the first study to directly link steamy programming to teen pregnancy...The researchers took into account other factors such as having only one parent, wanting to have a baby and engaging in other risky behaviors.

When most of pop culture is peddling sex, we need comprehensive sex education [it works] so teens at least have an idea of how to be safe.