Ultimately, the statistics for STDs and teenage pregnancy aren't promising. We are experiencing a record high of teenage girls with sexual diseases. Of the 18.9 million new cases of STDs each year, 48 percent occur among 15- to 24-year-olds. One in four teenage girls aged 14–19 and one in every two black teenage girls has an STD. Each year, almost 750,000 teen pregnancies are reported for women aged 15–19, and 82 percent of those pregnancies are unplanned.(3)
The MTV reality series Teen Mom, a spin-off of the wildly successful 16 and Pregnant, had the channel's highest-rated premiere in more than a year—evidence, I'd say, of our fascination with teenage motherhood. What happens behind these statistics, the feelings and motivations behind promiscuous behavior, and the direct results of it, is less clear. These are the dirty little secrets that girls carry. These are the stories they have—we have—but don't tell. There is some research that casual sex among teenagers can be more harmful than we've thought. The adolescent brain's prefrontal cortex—the part of the brain responsible for judgment—develops at an explosive rate. There are in fact only two times during development that the brain is overrun with synapses (neural connections) in this way: right before birth and right before puberty. At this critical time in preadolescence, the brain manufactures far more synapses than necessary. The synapses that are used become stronger. The ones that aren't used weaken and die. As a result, certain experiences become sealed in that teen's growth, in the strong synapses. If they handle intimacy—and sex—in ways that don't get them what they really want, again and again, they are likely to wind up with a potentially harmful approach to intimacy.(4)
What's more, the prefrontal cortex is not fully developed until the mid-twenties, and there is some evidence that bonding through sex and then breaking up again and again damages the ability to establish meaningful connection through intimacy. In other words, when teens bond and break, bond and break, before the cortex is fully developed, as most teens do, they potentially set themselves up for trouble with real intimacy later on. (This research, however, is based on findings concerning oxytocin, and many have argued that we don't know enough about oxytocin to make such claims. See the "References and Notes" section at the end of the book for more information.)5
At the same time, though, we know that a girl's ability to express her sexual desires is a necessary step toward developing healthy sexual intimacy, and it is essential if she is to protect herself against unwanted or unsafe sexual activities. In fact, in one study, researchers found that the fewer sexual partners a girl had, the more likely she was to not assert her beliefs and feelings during sexual activity, thereby potentially setting herself up for negative sexual experiences.(6)
Not all teenage sexual behavior derives from self-harm. Ideally, in fact, none of it would. Sexual curiosity and experimentation is a perfectly natural part of growing up. Girls have just as much sexual desire and curiosity as boys. They are curious about their genitals and others' as children. They masturbate. The hormones that race through a teenage girls' body create just as much sexual feeling as boys' hormones do.