WASHINGTON -- A new study mandated by Congress suggests that sexual abstinence programs in public schools may need some adjusting if they are to be successful.

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The Mathematic Policy Institute found that students who participated in sexual abstinence programs were just as likely to have sex a few years later as those who did not.

Students in elementary and middle schools from various demographic backgrounds took part.

The study found that youth in the program were no more likely than those outside the program to have abstained from sex.

Among those who reported having had sex, all had similar numbers of sexual partners and had initiated sex at about 14 years old.

Students in and out of the programs did not differ in the number of partners with whom they had sex.

About one-quarter of all youth in both groups had sex with three or more partners, and about one in six had sex with four or more partners.

Program and control group youths did not differ in their rates of unprotected sex, either at first intercourse or over the previous 12 months.

The report said that nationally, rates of teen sexual activity have declined over the past 15 years. Even so, about half of all high school youth report having had sex. And, one-quarter of sexually active adolescents nationwide have a sexually transmitted disease.