Edited sentence: "Of 12,000 teens, aged 12-18 years, who completed the TLW program, 88% had engaged in sexual intercourse before marriage within six years of completion.However,  a study by researchers from  Columbia University and Yale University found that young people who engage in virginity pledges have the same proportion of STDs as those who don't.However, virginity pledgers were actually more likely to engage in other sexual activities besides intercourse, namely oral sex and anal sex.Many argue that this leaves students with an inadequate education about sex.Some studies have also shown that students who engage in virginity pledges are less likely to use contraception and are less educated about safe sex than those who don't.Supporters of TLW point out that the program does not claim that abstinence is the only way to prevent pregnancy and STIs, simply that it is the only "foolproof" or absolutely sure method.The program has also begun providing public school teachers in the United States with lessons about sexual abstinence.The study found that virginity pledges delayed first intercourse by a year to 18 months.Therefore, critics contend that programs like True Love Waits fail from a STD and health point of view.They teach that sexual abstinence before marriage is the best way to prevent pregnancy and sexually transmitted infections (STIs).True Love Waits was named specifically in the aforementioned Yale Study for failing to prevent sex