Methods
This study used data from 60,973 adolescent participants in the National Survey of School Health. The response variable was sexual behavior, described in three categories (never had sexual intercourse, had protected sexual intercourse, had unprotected sexual intercourse). The explanatory variables were grouped into sociodemographic characteristics, number of risk behavior factors (regular use of alcohol, smoking, and experimenting with illicit drugs), and family and school context. Variables associated with having protected and unprotected sexual relations in each context were identified by means of multinomial logistic regression. The reference was "never had sexual intercourse