Adolescent Sexual Behavior Patterns in a British Birth Cohort: A Latent Class Analysis.

This study examined adolescent sexual behaviors patterns, and the consistency between sexual behavior and sexual orientation, in a prospective birth cohort. We used data on 5150 young people from the Avon Longitudinal Study of Parents and Children. Sexual orientation was assessed using a 5-point scale of sexual attraction at 15.5 years. Fourteen sexual activities were assessed using the Adolescent Sexual Activities Index at 13.5 and 15.5 years. Latent class analysis suggested four subgroups of adolescent sexual behaviors at 13.5: a "high-intensity sexual behaviors exclusively with other-sex, no same-sex intimacy" group (3.87%); a "moderate-intensity sexual behaviors exclusively with other-sex, no same-sex intimacy" group (16.57%); a "low-intensity sexual behaviors exclusively with other-sex, no same-sex intimacy" group (34.21%); and a "no sexual behavior" group (45.35%). There were five subgroups at 15.5 where four of them (23.42%, 18.37%, 28.12%, and 24.52%, respectively) were interpreted the same as at 13.5 years and a new "high-intensity sexual behaviors, some same-sex intimacy" subgroup (5.57%). Latent transition analysis showed approximately half the adolescents moved toward greater engagement in higher intensity sexual activities with other-sex at 15.5. Boys and girls who were in groups without same-sex intimacy were predominantly attracted to the other-sex, whereas there were moderate consistencies between same-sex intimacy and same-sex attraction for boys and low consistency for girls. Findings suggest that it may be important to include low-intensity sexual behaviors when assigning adolescents to sexual orientation groupings (via sexual behaviors) in order to reduce selection biases and increase statistical power via the increase in sample size.