WASHINGTON (Reuters) - A survey examining sexual practices of U.S. teens has undercut the notion that many engage in oral sex rather than intercourse to stay “technically” virgins, researchers said on Tuesday.

Teen girls are seen in a file photo. REUTERS/Jessica Rinaldi

The findings, published in the Journal of Adolescent Health, were based on answers by 2,271 females and males age 15 to 19 in 2002 in response to a government survey.

The researchers found about 55 percent of the teens said they had engaged in oral sex but that this practice was far more common among those who also had engaged in vaginal sex.

Teens said they began vaginal and oral sex at roughly the same time -- by six months after first vaginal intercourse, 82 percent had also engaged in oral sex, according to the study.

“There is a widespread belief that teens engage in nonvaginal forms of sex, especially oral sex, as a way to be sexually active while still claiming that, technically, they are virgins,” Laura Lindberg of the Guttmacher Institute in New York, who led the study, said in a statement.

“However, our research shows that this supposed substitution of oral sex for vaginal sex is largely a myth. There is no good evidence that teens who have not had intercourse engage in oral sex with a series of partners.”

The Guttmacher Institute studies sexual and reproductive health issues.

About one in 10 of the teens said they had engaged in anal sex. These teens were far more likely to have also engaged in vaginal sex.

“Teens of white ethnicity and higher socioeconomic status were more likely than their peers to have ever had oral or anal sex,” the researchers wrote.

Lindberg said the new findings illustrate that the Bush administration’s emphasis on school programs teaching sexual abstinence until marriage “does not give teens the skills and information they need to be safe.”

Statistics released by the Centers for Disease Control and Prevention in March showed that more than one in four U.S. teen girls was infected with at least one sexually transmitted disease. The CDC said in December the birth rate for U.S. teens rose in 2006 for the first time since 1991.

Lindberg said the Guttmacher Institute’s findings have health policy implications.

“While oral and anal sex carry no risk of pregnancy, engaging in these behaviors can nevertheless put teens at risk of sexually transmitted infections,” she said.

“Counseling and education should take into account total STI risk by addressing the full range of behaviors that teens engage in, including oral and anal sex.”