Making a virginity pledge may help some young people postpone the start of sexual activity, according to a new RAND Corporation study.

Researchers found that adolescents who made pledges to remain virgins until they are married were less likely to be sexually active over the three-year study period than other youth who were similar to them, but who did not make a virginity pledge, according to the study published online by the Journal of Adolescent Health.

"These findings do not suggest that virginity pledges should be a substitute for comprehensive sexual education programs, or that they will work for all kinds of kids" said Steven Martino, the study's lead author and a psychologist at RAND, a nonprofit research organization. "But virginity pledges may be appropriate as one component of an overall sex education effort."

While several previous studies have examined the impact of virginity pledges, the RAND Health study was uniquely designed to account for pre-existing difference between pledgers and non-pledgers on factors such as religiosity, parenting and friendship characteristics. The study tested the impact of virginity pledges by comparing pledgers with young people who had not made a pledge, but shared other characteristics with pledgers.

Researchers surveyed 1,461 adolescent virgins aged 12 to 17 in 2001 and reinterviewed participants one and three years later. About one-fourth of the group reported during the initial survey that they had made a virginity pledge.

Forty-two percent of those who did not make virginity pledges but were otherwise similar to those who did started sexual intercourse within three years, while just 34 percent of those who made virginity pledges reported having sexual intercourse within the same period.

"Making a pledge to remain a virgin until married may provide extra motivation to adolescents who want to delay becoming sexually active," Martino said. "The act of pledging may create some social pressure or social support that helps them to follow through with their clearly stated public intention."

Some researchers have speculated that abstaining from intercourse might increase participation in other sexual activities, like oral sex. But the RAND study found that those who pledged were no more likely to engage in non-intercourse behaviors than comparable youth who did not take a pledge.

"Waiting until you are older to have sex is good for teens from a health standpoint," Martino said. "There are lots of reasons for more kids to wait until they are older."

People who delay sex until they are older are less likely to have unintended pregnancies or contract a sexually transmitted disease, and are better equipped emotionally for the experience, according to researchers.

Martino said virginity pledges are unlikely to be a viable means to encouraging all adolescents to delay the initiation of sexual intercourse.

"Virginity pledges must be made freely for them to work," Martino said. "If young people are coerced or are unduly influenced by peer pressure, virginity pledges are not likely to have a positive effect."

Previous studies have suggested that adolescents who make virginity pledges may be less likely to use condoms during their first act of sexual intercourse. In the RAND study, adolescents who made virginity pledges but eventually had sex did not report lower condom use. But the RAND study only asked participants about condom use in the past year, not whether they used condoms the first time they had sex.

The first virginity pledge program in the United States began in 1993 and now includes hundreds of churches, schools and colleges. Estimates of U.S. adolescents suggest that 23 percent of females and 16 percent of males have made a virginity pledge.

Other authors of the RAND study are Marc N. Elliott, Rebecca L. Collins, David E. Kanouse and Sandra H. Berry. The study was supported by a grant from the National Institute of Child Health and Human Development.