Experts have opined that revelations that the 17-year-old daughter of Republican vice-presidential pick Sarah Palin is pregnant highlight the difficulties of getting American teens to just say "No."
News that Bristol Palin was expecting her first child thrust the issue of teenage pregnancy into the spotlight and exposed the schism between advocates of "abstinence only" and comprehensive sex education programs.
Alaska Governor Sarah Palin expressed opposition to explicit sex education in schools when asked if she supported abstinence only programs in 2006.
US lawmakers have provided hundreds of millions of dollars over the past decade to states wishing to promote "abstinence only" education in schools despite widespread skepticism over its effectiveness.
According to figures from Population Action International published in 2007, there were 44 births per 1,000 women aged between 15 and 19 in the United States between 2000 and 2005.
That is in stark contrast to Britain -- which is reported to have the highest rate in Europe -- with 27 births per 1,000 women.
Karen Hardee, vice-president of research for Population Action International told AFP that statistics cast doubt on "abstinence only" education.
"I always say that abstinence is effective if you can get people to abstain," Hardee said. "But there's so much data to show that it's not an effective tool in terms of reducing sexual activitity amongst teens."
The Washington-based National Campaign to Prevent Teen and Unplanned Pregnancy said in a statement three out of 10 girls in the United States become pregnant by age 20, with more than 729,000 teen pregnancies each year. About eight out of 10 teen pregnancies are unplanned, the campaign said.
John Santelli, MD, of the Mailman School of Public Health at Columbia University, said the "abstinence only" approach was increasingly discredited.
"The overwhelming weight of scientific medical evidence today is unsupportive," he told AFP. "They don't seem to be at all effective in terms of helping kids delay the initiation of sex."
Santelli accused advocates of abstinence of providing misinformation about contraception and noted that many US states had declined federal funding for implementing their own programs.
"There's such strong opposition in the public health education community that many states are turning away the federal money, which you don't see very often," Santelli said.
However, Linda Klepacki, a sexual health analyst for the Colorado-based evangelical movement Focus on the Family, argues that abstinence merely mirrors similar education programs aimed at teens regarding drugs and alcohol.
"With alcohol education we always speak to the fact that we want to avoid the risk altogether, so we counsel against drinking in any way until you're of age. It's exactly the same with drug education," Klepacki told AFP.
"Abstinence education flows right out of that risk avoidance approach -- we recommend teaching kids to avoid the risks altogether," she added.
Patricia Sulak, a professor of obstetrics and gynecology at the Texas A & M Health Health Science Center College of Medicine, helped draw up an abstinence-based education program for schools in Texas during the 1990s.
The "Worth the Wait" plan advocates abstinence as the healthiest choice for adolescents, encouraging teens to try everything from shopping, painting or going on a picnic as a "fun thing to do (besides having sex)."
However Sulak emphazises that the success of any sex education program is likely to depend on the support of outside influences, such as parents.
"You can have a two-week abstinence only curriculum in the school but what are they hearing for the other 50 weeks in the year?" she told AFP.
"The biggest determinant as to whether a kid has sex or not is not sex education -- it's parents. But parents aren't 100 percent effective either."
"I don't think abstinence is going to be effective until it's across the board, when healthcare professionals start saying 'You know what, why don't we all encourage kids to delay the onset of sex?'"