Via Research Blogging, psychology blogger Dr. Deb says

Uh oh. 

This is sure to spark some debate.

The sexual behavior of teenagers who pledge abstinence does not differ from that of closely matched non-pledgers. Moreover, pledgers are less likely to protect themselves from pregnancy and disease. 

Rosenbaum, J. (2009). Patient Teenagers? A Comparison of the Sexual Behavior of Virginity Pledgers and Matched Nonpledgers PEDIATRICS, 123 (1) DOI: 10.1542/peds.2008-0407

She said it here.

And while we’re at it, from the abstract of the actual paper by Rosenbaum. (Emphasis mine.)

OBJECTIVE. The US government spends more than $200 million annually on abstinence-promotion programs, including virginity pledges. This study compares the sexual activity of adolescent virginity pledgers with matched nonpledgers by using more robust methods than past research.

SUBJECTS AND METHODS. The subjects for this study were National Longitudinal Study of Adolescent Health respondents, a nationally representative sample of middle and high school students who, when surveyed in 1995, had never had sex or taken a virginity pledge and who were >15 years of age (n = 3440). Adolescents who reported taking a virginity pledge on the 1996 survey (n = 289) were matched with nonpledgers (n = 645) by using exact and nearest-neighbor matching within propensity score calipers on factors including prepledge religiosity and attitudes toward sex and birth control. Pledgers and matched nonpledgers were compared 5 years after the pledge on self-reported sexual behaviors and positive test results for Chlamydia trachomatis, Neisseria gonorrhoeae, and Trichomonas vaginalis, and safe sex outside of marriage by use of birth control and condoms in the past year and at last sex.

RESULTS. Five years after the pledge, 82% of pledgers denied having ever pledged. Pledgers and matched nonpledgers did not differ in premarital sex, sexually transmitted diseases, and anal and oral sex variables. Pledgers had 0.1 fewer past-year partners but did not differ in lifetime sexual partners and age of first sex. Fewer pledgers than matched nonpledgers used birth control and condoms in the past year and birth control at last sex.

CONCLUSIONS. The sexual behavior of virginity pledgers does not differ from that of closely matched nonpledgers, and pledgers are less likely to protect themselves from pregnancy and disease before marriage. Virginity pledges may not affect sexual behavior but may decrease the likelihood of taking precautions during sex. Clinicians should provide birth control information to all adolescents, especially virginity pledgers.

In particular the bit about 82% denying having ever pledged five years later is kind of… interesting. Wonder what the difference is between those who admit and those who deny pledging? So do I! But I’m not going to cough up the extortionate subscription price to look behind the federally-funded-but-somehow-still-for-profit firewall the publishers erect only because for some reason it’s legal.