The impact of the rise in abstinence-only education remains a question. To date, no published studies of abstinence-only programs have found consistent and significant program effects on delaying the onset of intercourse. In 2007, a study ordered by the U.S. Congress found that middle school students who took part in abstinence-only sex education programs were just as likely to have sex (and use contraception) in their teenage years as those who did not. Abstinence-only advocates claimed that the study was flawed because it was too narrow and began when abstinence-only curricula were in their infancy, and that other studies have demonstrated positive effects.