School-based sex education is associated with reduced risky sexual behaviour and sexually transmitted infections in young adults

Summary Objective To quantify the effectiveness of school-based sexual education on risky sexual behaviour and sexually transmitted infection (STI) acquisition in adulthood. Study design Online survey of sexual attitudes and behaviours. Methods Students at a British university were surveyed regarding where they learnt most about sex at 14 years of age, how easy they found talking about sexual issues with their parents and age at first intercourse. The effects of these factors were modelled on risk of recent unprotected intercourse and self-reported STIs in adulthood. Results Seventy-eight of 711 (11%) students reported unprotected intercourse in the 4 weeks before the survey, and 44 (6.2%) students had ever been diagnosed with an STI. Both age at first intercourse (risk reduced by 11% per year of delayed intercourse, 95% confidence interval (CI) 3–19%) and learning about sex from lessons at school (66% reduction in risk compared with learning from one's mother, 95% CI 5–88%) were associated with reductions in risk of unprotected intercourse. Factors associated with fewer STIs were age at first intercourse (17% reduction per year of delayed intercourse, 95% CI 5–28%); and learning about sex from lessons at school (85% reduction, 95% CI 32–97%), from friends of the same age (54% reduction, CI 7–77%) and from first boy/girlfriend (85% reduction, 95% CI 35–97%) compared with learning from one's mother. Conclusion School-based sexual education is effective at reducing the risk of unprotected intercourse and STIs in early adulthood. Influence from friends in adolescence may also have a positive effect on the risk of STIs in later life.