Abstinence education has no effect on US teenagers' sexual activity.

Tanne JH.
BMJ. 2007 Apr 28;334(7599):867.
Although the United States spends about $88m (£44m; 65m) a year teaching teenagers to abstain from sex outside marriage, young people in the programmes are just as likely to have sex as those who don't receive counselling, a new study says.
Teenagers who received abstinence education did not delay sexual activity any longer than those in a control group. When they became sexually active they had the same number of partners and were as likely to use condoms or other contraceptives as those who had not been counselled.
This rigorous, well designed study adds to and confirms previous research findings that abstinence only education programmes are ineffective and a waste of taxpayer dollars. It is called for more comprehensive programmes that not only teach abstinence but also provide information on contraception and safe sex.