Greater education about contraception is directly correlated to a decrease in risky sexual behavior among young adults, according to a new study.

But when researchers for the Guttmacher Institute surveyed 1,800 males and females aged 18-29, they found that more than half of young men and a quarter of young women proved to show little knowledge of contraceptive services. Six in 10 underestimated the effectiveness of oral contraceptives like birth control pills.

The more young people knew about contraception, the less likely they were to have unprotected sex: for every correct response on the survey, females' chances of expecting to have unprotected sex in the next three months decreased by 9 percent and the likelihood that she is using a hormonal or long-acting method of birth control increased by 17 percent.

Almost half of men and 69 percent of women surveyed said they were "committed to avoiding pregnancy," but for a significant number of them, that commitment doesn't come with precautionary measures, as 40 percent said birth control doesn't matter: "when it is your time to get pregnant, it will happen."

"Programs to increase young adults' knowledge about contraceptive methods and use are urgently needed," the study concludes. "Given the demonstrated link between method knowledge and contraceptive behaviors, such programs may be useful in addressing risky behavior in this population."

Abstinence-only sex education programs are often criticized for failing to prevent unintended pregnancies, resulting from misinformation or simply lack of information regarding contraceptives. The curriculum has also been found to teach that condoms have a 30 percent rate of failure, birth control pills can cause cancer and pregnancy could result from touching another's genitals.

Tennessee passed last week a bill that added language to the state's abstinence-only sex education curriculum warning against "gateway sexual activity." Although the legislation does not specifically define what "gateway sexual activity" comprises, many have interpreted the phrase to include discouragement of anything that has potential to lead to sex -- including kissing, hand-holding and cuddling.

Under the law, Tennessee teachers could be disciplined, and groups like Planned Parenthood could be fined up to $500 for promoting such "gateway" activity.

The Obama administration also recently reinvested in abstinence-only sex education by funding Heritage Keepers, after a study found that its curriculum delays sexual activity for some students. The organization "warns young women to 'wear modest clothing' to ward off 'lustful thoughts,' and assigns students wedding planning homework," according to Good.

CORRECTION: A previous version of the headline erroneously attributed the study results directly to abstinence-only sex education.