Although the analysis showed that pledgers delayed sexual intercourse, it also indicated that among those teens who eventually did begin to have intercourse, pledgers were less likely to use contraception than were non-pledgers.
"This analysis shows that virginity pledges can be an effective tool for delaying sexual intercourse in the teenage years," said Duane Alexander, M.D., Director of the NICHD. "The analysis has provided sound, substantial information for educators and others who work with youth to take into account when planning interventions to help teens to avoid early sex and its associated risks."
The analysis, conducted by Peter S. Bearman, Ph.D., now of Columbia University, and Hannah Brückner, Ph.D., now of Yale University, appears in the January American Journal of Sociology. The researchers conducted their analysis on information from the National Longitudinal Study of Adolescent Health (Add Health), a comprehensive survey of 90,000 seventh through twelfth graders. The survey was designed to measure the effects of family, peer group, school, neighborhood, religious institution, and community on behaviors that promote good health. Detailed information about the survey is available http://www.cpc.unc.edu/addhealth. A summary of the survey and other explanatory materials are available at http://www.nichd.nih.gov/new/releases/adolescent.html. Dr. Bearman co-designed the Add Health survey while he was at the Carolina Population Center of the University of North Carolina at Chapel Hill (UNC-CH).
The study found that as of 1995, more than two and a half million adolescents had taken spoken or written pledges to remain virgins until they marry. The Southern Baptist Church began the pledge movement and it has since grown to include hundreds of church, school, and college chapters. The movement is loosely organized around more than 80 independent organizations that sponsor public pledges and rallies.
"Early sexual intercourse increases the risk for unwanted pregnancy and sexually transmitted diseases such as AIDS," said Christine Bachrach, Chief of NICHD's Demographic and Behavioral Sciences Branch. "The research by Drs. Bearman and Brückner highlights a potential strategy for prevention efforts that should be tested further in experimental studies."
The two researchers began by analyzing information from adolescents who were virgins when the Add Health survey began. The researchers compared the likelihood of later having sexual intercourse among both pledgers and non-pledgers. The researchers noted that pledgers and non-pledgers differed in many respects.
Compared to non-pledgers, pledgers were more likely to be religious, of Asian ancestry, to score lower on a verbal vocabulary test, and to be in a romantic relationship. They were also less advanced in pubertal development, on average, than were non-pledgers. Dr. Bearman noted that three of these factors, independent of the virginity pledge, are likely to result in adolescents delaying sexual intercourse: being more religious, of Asian Ancestry, and less advanced in pubertal development. However, the differences between pledgers and non-pledgers did not account for pledgers' greater success in delaying sexual activity. When compared to non-pledgers having these same three characteristics, pledgers still were more likely to delay sexual activity a third longer than were non-pledgers.
The researchers found that the effectiveness of pledging among the youngest teens depended on the characteristics of their school. In socially "open" schools those in which students had a large number of friends and romantic ties outside the school the effectiveness of pledging increased with the number of students who pledged. In fact, each one percent increase in the proportion of students pledging resulted in a two percent increase in delaying sexual intercourse. Pledgers appeared to need the social support of fellow pledgers in order to remain abstinent.
The researchers observed a very different effect in socially "closed" schools. In these schools where most friendships and romantic ties occur within the school a higher percentage of pledgers actually decreased the pledge's effectiveness. If comparatively few adolescents in these schools pledged, pledging was effective in delaying sexual intercourse. However, if 30 percent or more of the students pledged, pledgers were no more likely to delay sexual intercourse than were non-pledgers. The researchers theorized that the pledge may appeal to some students because it gives them a unique identity, apart from the crowd. After too many of their fellow students joined them in pledging, abstinence lost its special appeal. The researchers noted that socially closed schools are in the minority, composing only 30 percent of schools in the survey.
"Once the pledge becomes normative, it ceases to have an effect," Bearman and Bruckner wrote. "The pledge identity is meaningful, consequently, only if it is a minority identity, a common situation for identity movements."
The researchers also examined the consequences of breaking a pledge. Previous studies have found that girls who began having sex experienced a slight decrease in self-esteem. Teens who broke their pledges, however, suffered no greater loss of self-esteem than did non-pledgers who began having sexual intercourse.