Sexual practice associated with knowledge in adolescents in ninth grade

The aim of the present study was to reveal any association of sexual practice with knowledge about sex education, reproductive physiology and abortion. The study was performed in a non-intervention setting to minimize information bias. A cross-sectional questionnaire was handed out without prior notice to all ninth grade pupils in the Municipality of Viborg, Denmark, in 2007. We found that sexual debut was associated with a greater probability of knowing that chlamydia is the most common sexually transmitted infection (STI). Knowledge of chlamydia was strongly associated with knowledge about the first symptom of pregnancy. A high general level of knowledge of STI was associated with the father being the source of the knowledge among pupils who had not yet had their sexual debut (p < 0.04) and among girls (p < 0.04). The general of knowledge of STI was associated with knowing the first signs of pregnancy and the criteria for legal abortion. A high level of knowledge of STI was significantly associated with the use of contraceptives to avoid pregnancy. The vast majority of condom users (81% compared to 56% of pill users) stated protection against STI as a reason for using contraception (p < 0.006). Concern about the partner's opinion was more outspoken among condom users than among pill users (19% versus 6%, condom versus pill users, p < 0.035). Discrepancy between sexual knowledge and practice is a fact. The discrepancy, however, varies according to sexual experience, gender and whether the respondent's actual behaviour aimed at avoiding unwanted pregnancy or STI.