A new study finds an abstinence-only intervention for pre-teens was more successful in delaying the onset of sexual activity than a health-promotion control intervention.

In the study to evaluate the controversial approach to sex education, researchers found that after two years, one-third of the abstinence-only group reported having sex, compared to one-half of the control group.

Abstinence-only interventions may have an important role in delaying sexual activity until a time later in life when the adolescent is more prepared to handle to consequences of sex,  said lead author John B. Jemmott III. This can reduce undesirable consequences of sex, including pregnancy and sexually transmitted infections like HIV/AIDS.

While abstinence-only intervention did not eliminate sexual activity all together, this is the first controlled study to demonstrate that an abstinence-only intervention reduced the percentage of adolescents who reported any sexual intercourse for a long period, in this case two years, following the intervention.

Significantly, researchers determined that none of the interventions had significant effects on consistent condom use or unprotected sex.

This takes away the main pillar of opposition to abstinence education, said Robert Rector, a senior research fellow at the Heritage Foundation who wrote the criteria for federal funding of abstinence programs. I've always known that abstinence programs have gotten a bad rap, he told the Washington Post.

There was a 33 percent reduction in self-reported sexual intercourse from the abstinence-only group, compared to the control group, by the end of the study.

Of the students who reported that they were sexually active during the study, there were fewer reports of recent sexual activity from the abstinence-only intervention participants (20.6 percent) compared to the control participants (29.0 percent).

Policy should not be based on just one study, but an accumulation of empirical findings from several well-designed, well-executed studies, said Dr. Jemmott.

The abstinence-only intervention was based on principles shown to be effective in reducing the risk of sexually transmitted infections (STIs), including HIV/AIDS, and did not use a moralistic tone or portray sex in a negative light.

It encouraged abstinence as a way to eliminate the risk of pregnancy and STIs.