NEW YORK (Reuters Health) – Comprehensive sex education that includes discussion of birth control may help reduce teen pregnancies, while abstinence-only programmes seem to fall short, the results of a US survey suggest.

Using data from a 2002 national survey, researchers found that among more than 1,700 unmarried, heterosexual teens between 15 and 19 years old, those who'd received comprehensive sex ed in school were 60 percent less likely to have been pregnant or gotten someone pregnant than teens who'd had no formal sex education.

Meanwhile, there was no clear benefit from abstinence-only education in preventing pregnancy or delaying sexual intercourse, the researchers report in the Journal of Adolescent Health.

The study found that teens who'd been through abstinence-only programmes were less likely than those who'd received no sex ed to have been pregnant. However, the difference was not significant in statistical terms, which means the finding could have been due to chance.

In addition, there was no evidence that comprehensive sex education increased the likelihood of teen sex or boosted rates of sexually transmitted diseases (STDs) – a concern of people who oppose teaching birth control in schools.

While comprehensive sex ed did not clearly reduce the STD risk, there was a modest, but statistically insignificant reduced risk of engaging in sex. The abstinence-only approach had no effect on either factor, the researchers found.

"The bottom line is that there is strong evidence that comprehensive sex education is more effective than abstinence-only education at preventing teen pregnancies," said lead researcher Pamela K. Kohler, of the Center for AIDS and STD at the University of Washington in Seattle.