Comprehensive sexual education programs are more effective than abstinence-only programs at reducing teen pregnancy and STD rates. Abstinence-only programs teach that abstaining from sex is the only way to avoid pregnancy and STDs, and have teens take a "virginity pledge." However, only a third of teens who take the pledge actually abstain from sex. Comprehensive programs teach abstinence as the best option but also educate about contraceptives. Teens receiving comprehensive education are less likely to report unplanned pregnancy, and are more likely to delay sex or have less frequent sexual activity.