A federal study found that teenagers who pledged abstinence are just as likely to have premarital sex as those who do not make the pledge, HealthDay News reported.

Those teenagers who originally made the pledge are significantly less likely to use condoms or birth control than teens who did not make the pledge.

"Previous studies found that pledgers were more likely to delay having sex than non-pledgers," said study author Janet E. Rosenbaum, a post-doctoral fellow at the Johns Hopkins Bloomberg School of Public Health. "I used the same data as previous studies but a different statistical method."

Rosenbaum said she compared teens who had taken a virginity pledge with similar teens who had not taken a pledge, but were apt to delay having sex.

She did not include teenagers who were unlikely to make a promise to abstain.

"Virginity pledgers and similar non-pledgers don't differ in the rates of vaginal, oral or anal sex or any other sexual behavior," Rosenbaum said. "Strikingly, pledgers are less likely than similar non-pledgers to use condoms and also less likely to use any form of birth control."

Her report will be published in the January issue of the journal Pediatrics.

Rosenbaum gathered data from the National Longitudinal Study of Adolescent Health on 934 high school students who had never had sex or had taken a virginity pledge.

She noticed after five years that the teens that made a promise to abstain did not differ from teens who had not taken a pledge in rates of premarital sex, including oral and anal sex, or sexually transmitted diseases.

Teens who took the pledge began having sex at the same age as non-pledgers, Rosenbaum said, although they had 0.1 fewer sex partners during the past year then their non-pledger counterparts.

However, pledgers were 10 percent less likely to use condoms or any other form of birth control. And five years after making the pledge, 80 percent of pledgers denied making such a promise.

Bill Albert, chief program officer for The National Campaign to Prevent Teen and Unplanned Pregnancy, said teens need to be encouraged to delay having sex, but they also need to be given the facts about safe sex.

"When pledgers fell off the wagon, they fell off hard," he said. "What have we gained if we encourage young people only to delay sex until they are older, but when they do become sexually active, they don't protect themselves or their partners?"

Click here to read more on this story from HealthDay News.