Background: Early adolescence is a critical stage in adolescents. This is the phase at which many young people start their sexual life early, increasing the risk of sexually transmitted infections and unintended pregnancy. Few studies have analyzed the factors associated with early sexual initiation in very young adolescents in low- and middle-income countries. Therefore, this study assessed the early sexual initiation stratified by sex and its correlates in a sample of Brazilian adolescents.
Methods: The study sample included Brazilian adolescents aged 12-14 who participated in The Study of Cardiovascular Risk in Adolescents (ERICA), a multicenter, school-based, country-wide, cross-sectional study. Early sexual initiation was defined as the first sexual intercourse at or before 14 years old. Multivariate logistic regression was used to identify independent factors associated with early sexual initiation.
Results: The prevalence of early sexual initiation was 7% among girls and 18% in boys. In a multivariate analysis, the adolescent's age, mother's schooling, smoking, alcohol consumption, and Tanner Stages were associated with early sexual initiation for both boys and girls. For girls, living with both parents, common mental disorders, and age at menarche were predictors of early sexual initiation, while race and type of school were correlated to early sexual initiation only for boys.
Conclusions: The early sexual initiation was associated with sociodemographic, lifestyle risk factors and secondary sexual characteristics in both sexes, while there were differences between the predictors of early sexual initiation among girls and boys. It emphasizes the importance of sex education and promotes healthy lifestyles in environments through families and schools in early adolescence.