LAUSR

Objectives Sexual activity is an important integrative behaviour that interacts with biological, psychological and social factors among various changes in adolescence. However, starting sex at an early age is associated with adverse outcomes. Thus, this study aimed to investigate the factors associated with adolescents’ sexual experience based on the biopsychosocial model. Design A cross-sectional study. Setting The participants were selceted through a complex sample design at high schools and middle schools nationwide in Korea. Participants We employed 4-year data (2017–2020) of the cross-sectional Korea Youth Risk Behavior Web-based Survey. In total, 234567 participants attending middle school and high school were analysed. Sexual experience was defined as having had sexual intercourse (oral, anal or vaginal) in their lifetime. To identify variables associated with adolescents’ sexual experiences, we used a biopsychosocial model. Logistic regression analysis was performed to identify the variables associated with sexual experience. Results 3.4% of boys and 1.6% of girls attending middle school had sexual experiences, showing a significant difference. A total of 10.4% of boys and 5.1% of girls attending high school had sexual experiences (p<0.001). Among the biological factors of the biopsychosocial model, age and gender were significantly associated with sexual experiences in adolescents. Regarding the psychological factors, suicidal thoughts were a significant risk factor associated with sexual experience. Furthermore, social factors including drinking, smoking and family structure were associated with sexual experience in adolescents. Particularly, a significantly higher sexual experience was found in the three groups living with a single parent, step-parents and no parents compared with the group living with both parents in family structure. Conclusions This study demonstrated the factors associated with adolescents’ sexual experience based on the biopsychosocial model. Further research and policy strategies that consider supporting family communication and mental health and preventing substance use are required to prevent adolescents’ sexual health.