Study Debunks Theory On Teen Sex, Delinquency

But those are risks that other nations have mitigated with education, Harden and Turkheimer said, while U.S. educators wanting a piece of the nation's $200 million "abstinence only" budget must adhere to a curriculum that links sex to delinquency and explicitly precludes discussion of contraception.

The new study "really calls into question the usefulness of abstinence education for preventing behavior problems," Harden said, "and questions the bigger underlying assumption that all adolescent sex is always bad."

Similar re-analyses have begun to undermine other conventional notions about health.

A recent study by Scottish researchers asked whether the higher IQs seen in breast-fed children are the result of the breast milk they got or some other factor. By comparing the IQs of sibling pairs in which one was breast-fed and the other not, it found that breast milk is irrelevant to IQ and that the mother's IQ explains both the decision to breast-feed and her children's IQ.

In another example, Arline Geronimus, a University of Michigan professor of health behavior who is now a fellow at Stanford University's Center for Advanced Study, knew that babies born to teenagers are more likely to die in their first year of life than those born to older women.

"But that is an apples-to-oranges comparison," she said. In New York City, for example, far more teen mothers live in Harlem than on the Upper East Side, she said, and "there are a lot of differences between those groups."

So Geronimus looked more closely and got a different answer.

"If you compare Harlem teen moms to Harlem older moms, you find that the kids of the teen moms are actually less likely to die," she said. The reasons include the fact that, unlike older women, poor teenagers are generally not juggling jobs and have older relatives to help.

It can make sense for poor women to have children when they are quite young, Geronimus concludes, and any effort to change that ought to treat it as an economic problem, not a health education problem.

In a different re-analysis, Geronimus made another counterintuitive finding. While it is true that, in general, teen mothers are less likely to breast-feed their babies than older moms, it is not true among poor women. Poor teenagers are actually more likely to breast-feed than poor older moms, in large part because the older women have jobs that don't grant them the time to breast-feed or pump milk.

Because of that misconception, programs promoting breast-feeding have targeted teens instead of older women, Geronimus said. And they have taken aim, in part, at a concern that teenagers were believed to have: the cosmetic effects of breast-feeding on their breasts.

"So you've targeted the wrong population," Geronimus said, "and come up with the wrong kind of intervention."