NEW YORK (Reuters Health) - Teens who take a pledge to remain a virgin until marriage may in fact be more likely than their peers to delay sex, according to a U.S. study.

Investigators at the RAND research institute found that even among U.S. teenagers with similar backgrounds and values, those who'd taken a virginity pledge were less likely to start having sex over the three-year study period.

"Our data suggest that it is a good idea for teens who are inclined to delay sex to make a pledge, because they're more likely to delay sex if they do so," lead researcher Dr. Steven C. Martino said in a statement. "A public statement or commitment to do -- or not do -- something makes it more likely that you will follow through on your stated intention."

On the other hand, virginity pledges alone are not enough to prevent teen pregnancies and sexually transmitted diseases, noted Martin of RAND in Pittsburgh, Pennsylvania.

"You also need a comprehensive program of sexual education for young people who are not inclined to delay sex and for virginity pledgers who eventually break their pledge," Martino said.

The findings, published in the Journal of Adolescent Health, are based on telephone surveys of 1,461 U.S. teenagers who were interviewed at the beginning of the study and again one and three years later.

The adolescences were selected to reflect a nationwide sample; 68 percent were white, 47 percent were female, 14 percent were African American, 12 percent were Hispanic and 6 percent were "other." One third had a parent with a college degree and nearly two thirds had parent with some education after high school.

During the first interview, they were questioned about their sexual history and about characteristics that would make them more or less likely to take a virginity pledge -- factors such as how many of their friends were sexually active, how involved they were at school and church, and their parents' attitudes toward premarital sex.

Martino's team found that even among teens who had values that made them more likely to take a virginity pledge, those who actually took one were more likely to delay having sex.

Of the former group, 42 percent started having sex during the study period. In contrast, one third of "pledgers" did.

Among those pledgers who did have sex, the rate of condom use was similar to that of other sexually active teens -- suggesting that taking such a pledge does not diminish teenagers' knowledge about safer sex.

"Making a virginity pledge appears to be an effective means of delaying sexual intercourse initiation among those inclined to pledge without influencing other sexual behavior," Martino and his colleagues conclude.

An estimated 23 percent of teenage girls and 16 percent of teenage boys in the U.S. have taken a virginity pledge, according to the researchers. Hundreds of churches, schools and colleges across the country now advocate them.

SOURCE: Journal of Adolescent Health, October 2008.

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