[Factors associated with age at first intercourse: a population-based study]

First sexual intercourse is considered an important event in young people's lives and has occurred at an increasingly early age. The aim of this study was to identify factors associated with early age at first intercourse in individuals 18 to 24 years of age in Pelotas, Rio Grande do Sul State, Brazil. This was a population-based cross-sectional study in a representative sample of 1,621 young people from August 2007 to December 2008. Subjects answered a questionnaire on health behaviors, including items related to their sexual lives. Cox regression was used to assess the association between early age at sexual initiation. After multivariate analysis, variables that are directly related to early sexual initiation were: male gender, low socioeconomic status, low schooling, divorced parents, living with a partner, not practicing a religion, smoking, drug use in the previous three months, and non-use of condoms during last intercourse. Considering the current social context, the study highlights the need for adequate sexual orientation with a preventive approach.