Harvard graduate student Janet Rosenbaum analyzed data on a nationally representative sample of seventh through 12th graders collected in the National Longitudinal Study of Adolescent Health. Nearly 15,000 teens were interviewed in 1995 and again in 1996.
In the first survey, 13% of teens said they'd taken a virginity pledge. A year later, 53% of them said, "What pledge?"
On the other hand, about a third of teens said they'd had sex. A year later, 10.5% of these kids said they were virgins.
"Among those who take a virginity pledge, a year later more than half said they had never taken such a pledge," Rosenbaum tells WebMD. "And just over 10% of those who said they had sex later said they didn't have sex."
Rosenbaum's report appears in the June issue of the American Journal of Public Health.
Role of Religion
What makes a teen forget a virginity pledge? Sex certainly plays a role. Virgin teens who became sexually active were three times more likely to deny pledging than teens who said they'd remained virgins.
Strong religious messages may also play a role. Kids who said they no longer were born-again Christians were more likely to deny virginity pledges than other teens.
"I found that people who had become sexually active or who were already sexually active were more likely to retract their virginity pledges," Rosenbaum says. "Those who changed from being born-again Christian to other denominations were more likely to retract their pledge."
On the other hand, becoming a born-again Christian -- or taking a virginity pledge -- was linked to teens retracting self-reported sex.
"Looking at people who retracted reports of having sex, those who took virginity pledges in either survey were more likely to retract -- as was becoming a born-again Christian," Rosenbaum says. "So it seems that when social circumstances change, it affects people's reports on surveys of their own behavior."
Teens and Change
Teen changeability doesn't surprise Thomas Smith, PhD, professor of social work at Florida State University, Tallahassee. Smith recently reviewed 14 scientific studies of abstinence education.
"Is the difference in answers one year apart indicating a change in the mood of these kids? Probably not," Smith tells WebMD. "It is probably more about what they had for breakfast on that day. Teens are very labile on what they do or say at any one time."
Smith says that only strong messages get across to teens. That, he says, is why the strong anti-premarital-sex position of fundamentalist Christian religion makes an impression on them.
"The more memorable a message is, the more likely a child will abstain from sex," Smith says. "If you are from a fundamentalist denomination, there is less likelihood your child will engage in premarital sex. That may be because the mores of this religion are so strong. But after they leave the protective nest of their observant household, they may go wild with experimentation. Not just with sex but with alcohol, drugs, whatever."
Strong religious attitudes toward sex also may make teens more reluctant to admit to having begun sexual activity, says obstetrician-gynecologist Sylvana Bennett, MD, of the University of California, San Diego Medical Center. Bennett studies teen-prevention programs.
"Demonizing sexual activity makes it hard for teens to be honest," Bennett says. "So the teen goes into the doctor with a genital rash but says, 'No, I have never had sex.' There is where the real health problem comes in. It creates a barrier to open communication to have that expectation of abstinence."
Bennett also notes that religious teens who say they are virgins -- even though they previously said they'd had sex -- aren't hypocrites.
"When kids come into religion, they are actually told that if they take the virginity pledge they are born-again virgins. God wipes their sex away," Bennett says. "Sexually experienced teens who say, 'I have never had sex,' aren't lying -- they go into denial."
Can Abstinence Education Work?
The unreliability of teen's self-reported sexual behavior makes it nearly impossible to evaluate abstinence education programs, Smith says.
"Given the lack of consistent responses, and given the difficulties of interpreting study results, it is hard to say if abstinence education is effective or not," he says. "Would I bet my money that a teen of 16 is really going to be affected by an abstinence message? No way. She is probably already having sex."
But even though Smith is pessimistic about evaluating these programs, he does believe they can have an impact.
"You can't really prevent risky behavior by adolescents completely. But if you can delay it as long as possible, the better the chance a kid will maintain safe sexual behavior going into adulthood," he says. "It is an uphill battle. By the time most kids are in their later teen years, sexual abstinence or delay already is a lost cause."
Bennett finds that both abstinence-only education and abstinence-plus-sex education work. However, when kids do have sex, those who got the abstinence-plus education are better off.
"Both types of program seem to work, but in teens already having sex or those who start sex, those exposed to abstinence-plus were much more likely to use," she says. "Both abstinence-only and abstinence-plus programs seem to decrease sexual activity, but in teens that do end up having sex, they are worse off without safe-sex information."
Parents, Smith and Bennett each note, are very likely to think that teens interpret sexual education as permission to have sex. This isn't the case, Bennett says.
"In 27 studies I reviewed, kids in abstinence-plus programs are not more likely to initiate sex," she says. "The idea kids will take safe-sex information and have wild, rampant sex -- that is not supported in the scientific literature at all."