What do Britney Spears, George W Bush, Hillary Clinton, school superintendents, state governors of all political persuasions and parents from Alabama to Alaska have in common? Why, their opposition to sex before marriage - in theory, at least.

Britney’s vow to remain chaste until she ties the knot, as she bumps and grinds her way through her adolescence in the music business, is one of the great mixed messages of our times. But it goes down well with the US government, the fundamentalist right and the unprecedented numbers of school districts that are promoting abstinence-only sex education in an attempt to reduce the level of teenage pregnancies.

And down it is certainly going. Between 1991 and 1996, the number of teenage pregnancies fell by 11.9 per cent across the country, and in some states by more than 16 per cent. The number of teenage abortions also fell by more than 15 per cent.

Those who argue that saying no is the only form of safe contraception point to these figures as proof that their approach is effective. They claim that young people’s sexual behaviour has changed as a result of the adoption of abstinence-only programmes. But such programmes have become widespread only since 1996, when federal funding came on stream.

The likeliest explanation for the fall in teenage pregnancies is that youngsters are responding to the safe-sex message generated by an aggressive HIVAids education programme, introduced in the mid-Eighties. The continuing fall, says Tamara Kreinin, president of Sexuality Information and Education Council of the United States (SIECUS), reflects the availability of contraceptives and young people’s tendency to delay sexual activity at times of economic boom. “Kids are seeing that there are other, better, more interesting things to be involved in,” she says. Even so, the “just say no” movement is on the march, backed by the ultra-right and church groups and by generous federal funding - a whopping $440 million (pound;303 million) over five years and a further $50 million (pound;35 million) in a separate congressional bill this year.

One in three school districts uses an abstinence-only curriculum in which sex is portrayed as a vehicle for Aids and sexually transmitted diseases. Contraception is discussed only in terms of its failures. Fewer than one state school in two gives students information on how to access birth control and only 39 per cent on how to use a condom.

At a White House ceremony in 1997, the Best Friends programme was named as one of the most effective abstinence-only approaches by the National Campaign to Prevent Teenage Pregnancy. Like most, if not all, abstinence-only programmes, it’s aimed exclusively at girls, a curiously one-sided approach to getting young people to change their behaviour.

The focus of the 12-year-old programme is social development and character-building. It aims to help adolescent girls develop skills - critical thinking, decision-making, collaboration, goal-setting - that will enable them to avoid at-risk behaviour, specifically alcohol, drugs and sex. It also builds their self-respect by involving them in community service activities and provides them with a trusted adult in whom they can confide. The programme is introduced at the upper end of elementary school, where it slots into the timetable. In middle and high schools, it’s run as an after-school and weekend activity.

Best Friends’ message is succinctly illustrated in the lyrics of the Best Friends Theme Song, which the girls sing as they perform a synchronised dance routine to round off each session: Don’t you believe that lie: “sex is the same as love” You’ve got your life to wait until the time is right Love starts with self-respect no one can give you that Listen to the voice that says: “Wait ‘til it’s time“Don’t give in to wisdom from the crowd when they pull you down Just listen to... BEST FRIENDS BEST FRIENDS BEST FRIENDS.

There’s not a lot of subtlety about Best Friends. Its logo and image evoke Barbieville, all pink, rosy and sexless. There’s a lot of army drill-style call and response. After showing a class of 10 and 11-year-olds at Beechfield elementary school in Baltimore a video on the dangers of drugs, Best Friends leader Larrice Harris calls out: “Will you smoke marijuana?” to which the girls roar back: “NO!” “Best friends have what?” “Self control!” “We don’t do the D word. What don’t we do?” “Drugs!” The number of girls in the programme is small - fewer than 5,000 in 14 states. But its own figures suggest that this brand of behaviour modification mixed with social and emotional development is doing the trick. In Washington DC, for instance, where the high-school pregnancy rate runs at 18 per cent, the rate among Best Friends participants is 1 per cent.

Schools have to buy the programme in, using federal funds, which covers some of the staffing costs, training, a curriculum manual and T-shirts with logos. At Beechfield elementary, fundraising makes up the shortfall.

Sex Can Wait is similar to Best Friends in its focus on building skills and self-esteem. Unlike Best Friends, it’s aimed at boys as well as girls. A five-times winner of an award for outstanding work in community health promotion from the US Department of Health and Human Services, it uses material that appears more sophisticated than Best Friends, and its effectiveness has been more rigorously evaluated. Findings show that it has an impact on “recent sexual behaviour”, meaning that fewer middle school students (aged 11-14) in the Sex Can Wait group had sex in the previous month than those in a control group.

But if you want to find an abstinence programme that conforms to all your stereotypes of Moral Majority propaganda, True Love Waits takes some beating.

Run by Lifeway Christian Resources in Nashville, Tennessee, it’s an out-of-school phenomenon with its own “it’s cool to be a virgin” website, on which young people pledge to be chaste until marriage. The great news is that if you have already had sex, you can still be a secondary virgin (sic) through the grace of God.

True Love Waits is an international movement involving hundreds of thousands of young people. Although not delivered as a sex education programme in schools, it runs an annual campaign aimed at school students. When students at the Christian Fellowship high school in Milwaukee were denied access to the intercom to make announcements about the campaign and were banned from displaying pledge cards, they filed a lawsuit against the school and the school district, claiming censorship and violation of the first amendment.

But, despite media rumours, it is not a road that we in Britain are about to go down. Health minister Yvette Cooper has denied reports that the Government is to spend pound;2 million on a “just say no” campaign, insisting that such an approach is patronising and ineffective. Her department has opted instead for a campaign that will give teenagers the facts and is aimed at boys as well as girls.

But there’s strong evidence that information alone fails to affect behaviour. One of the most successful and enduring teenage pregnancy prevention projects in the US, the 20-year-old Teen Outreach Programme (TOP), uses active or “service” learning in the community as the vehicle for raising young people’s self-esteem and altering the way they behave.

The project work is tied in with the curriculum, so they use maths, science and English skills in the project, then bring their learning back into the classroom for discussion and evaluation. They also have a specially trained facilitator who’s not part of the school staff.

While sex education, along with social and emotional development work, is an intrinsic part of the TOP programme, it isn’t the focus. But its impact on sexual behaviour is impressive. Participants in TOP are 33 per cent less likely to get pregnant or engage in sexual activity, 11 per cent less likely to fail courses and 60 per cent less likely to drop out of school than those in a comparable control group.

“TOP,” says Tamara Kreinin of SIECUS, “is one of the best, because it gives young people something meaningful to do, something they enjoy doing and someone significant in their lives to talk to. It also acknowledges the complexities of why young people become sexually active and how it’s just as important to reach out to boys as to girls.”

It’s all a long way from condoms and bananas. Welcome to Barbieville.