Young women who break an abstinence pledge may be more at risk of unwanted pregnancies and sexually transmitted diseases (STDs) than peers who have never taken such a pledge in the first place, scientists claim. In the United States, about 12% of adolescent girls vow not to have sex before marriage, but up to 88 % of them end up breaking this promise.

In a study published in the Journal of Marriage and Family, scientists have analysed the health data of more than 20,000 American teenagers to assess the impact that taking a virginity pledge has on female sexual health. In particular, they wanted to determine whether "pledgers" were less likely to become pregnant outside marriage or to test positive for a common STD – the human papillomavirus (HPV).

In the US, sexual education is often a source of controversy. The CDC recommends in-school programs focusing on the prevention of STDs and pregnancy, including educating on condom-use. The problem is that this initiative is not always well accepted. In fact, only about half of high schools and one-fifth of middle schools provide sexual health education that meets CDC criteria, with abstinence often being the only other alternative presented to teenagers.

By identifying a high risk of pregnancies outside marriage and significant rates of HPV in pledge-breakers, the latest research provides new critical evidence that abstinence-only policies are not effective to promote healthy sexual behaviours in adolescents.

HPV screening and pregnancies

Scientists looked at data from a nationally representative, longitudinal study of adolescents. These included information collected between 1994 and 1995 when 20,745 students in grades 7 to 12 – between 13 and 18 years old – answered questions regarding their health, romantic relationships and whether they had taken abstinence pledges.

Between 2001 and 2002, 15,197 of them were re-interviewed. The researchers specifically focused on female participants, looking at their HPV screening results and whether they had become pregnant at any time outside marriage. They then compared the results of women who had never taken an abstinence pledge and those who did, but ended up breaking it.

Overall, HPV rates did not differ significantly, with about a quarter of girls testing positive in each group. However, when the researchers focused on young women who had had two or more sex partners, pledge-breakers tested positive for HPV in higher proportions. Additionally, 30% of pledge-breakers – compared to 18% of non-pledgers – became pregnant outside marriage, in the six years after they began having sex.

Dangers of abstinence only policies

According to the authors, these findings suggest young girls who have broken an abstinence pledge may engage in riskier sexual behaviours than girls who never vowed abstinence.

They may be less prepared and less aware of how to deal with the risks of sexual activity, because abstinence-policies often go hand in hand with a rejection of condoms and other contraceptives. Since a majority of pledgers break their promise to stay virgins until marriage, this can have important, unintended health consequences.

"If adolescents either are provided inaccurate information about condom use or contraception or are socialised to be hostile to these practices, they could be in a bind when they break pledges, as almost all of them do", the scientists conclude.