Sex education greatly boosts the likelihood that teens will delay having intercourse, according to a new study that is the first of its kind in years.

Male teens who received sex education in school were 71 percent less likely — and similarly educated female teens were 59 percent less likely — to have sexual intercourse before age 15. Males who attended school, meanwhile, were 2.77 times more likely to rely upon birth control the first time they had intercourse if they had been in sex-education classes.

“Sex education seems to be working,” said study lead author Trisha Mueller, an epidemiologist with the Centers for Disease Control and Prevention. “It seems to be especially effective for populations that are usually at high risk.”

The researchers found that sex education reduced by 91 percent the risk that African-American females in school would have sex before age 15. In general, however, sex education appeared to have no effect on whether female teens used birth control.

According to Mueller, earlier large-scale research into the effectiveness of sex education relied on data from the 1970s to the early 1990s. Those studies suggested that sex education was not very effective at delaying sex, she said.

The new study looked at a sample of 2,019 teenagers ages 15 to 19 years, who responded to a survey during a 2002 national study.

The researchers analyzed the possible effects that sex education had on the sex lives of teens and adjusted the results to account for the effects of factors like the wealth of their families.

The study did not explore the hottest debate in sex education: whether classes should teach about contraception or focus entirely on abstinence. Students received sex education if they had either or both types of instruction, according to the study.

While the study suggests a link between sex education and sexual behavior, researchers did not design it to prove a cause-and-effect relationship between the two definitively.

Claire Brindis, interim director of the Philip R. Lee Institute for Health Policy Studies at the University of California at San Francisco, said sex education remains important because kids still harbor “mythology” about sex. “Some still believe you can’t get pregnant if you’re standing up or doing it for the first time or if your boyfriend is drinking a lot of Mountain Dew.

“A lot of sex education is about the plumbing — teaching them about anatomy and physiology, what a condom looks like,” Brindis said. “What they really need help on is: ‘I’m in the back seat or I’m at a party, and there aren’t adults around and there’s pressure to do more than make out.’ They need help with ‘What do I do in that setting?’”

Journal reference: Mueller TE, Gavin LE, Kulkarni A. The association between sex education and youth’s engagement in sexual intercourse, age at first intercourse, and birth control use at first sex. J Adolesc Health 42(1), 2008.