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Ann Epidemiol. 2013 Oct;23(10):629-35. doi: 10.1016/j.annepidem.2013.03.009. Epub 2013 Apr 24.

Contextual factors associated with sexual behavior among Brazilian adolescents.

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Department of Public Health, School of Medicine, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil; Research Group on Chronic and Occupational Diseases - GERMINAL, Universidade Federal de Minas Gerais, Belo Horizonte, Brazil. Electronic address:



There are few studies about the influence of the context on sexual behavior among adolescents in developing countries, such as Brazil. Adolescent pregnancy and the high incidence of sexually transmitted disease (STDs) among Brazilian youngsters are a public health problem. The object of this study was to investigate whether factors from family and school contexts are associated with sexual behavior among Brazilian adolescents.


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."


Approximately one fourth of adolescents have already had sexual intercourse, most frequently boys. Among the adolescents who declared sexual initiation, the most part had their first sexual relation with age of 13 years or younger. Almost 21% did not use protection the last time they had sex. The greater the number of risk factors involved, the higher the incidence of protected and unprotected sex. In the family context, living with only one or with neither parent and low parental supervision increased the frequency of protected and unprotected sex. Never eating meals with the parents augmented the incidence of unprotected sex (odds ratio [OR], 1.60). In the school context, students from private schools were less likely to have had protected and unprotected sex (OR, 0.58 and 0.68). Not receiving instructions at school about pregnancy prevention increased the frequency of protected and unprotected sex (OR, 1.33 and 1.74, respectively).


Family and school context factors are associated with sexual behavior. These associations are generally stronger for unprotected sex. Information about the prevention of pregnancy and STDs/AIDS has to be disseminated very early owing to the young age of sexual initiation.


Adolescent; Adolescent pregnancy; Condom; Context; Family; School; Sexual behavior; Sexual risk; Sexually transmitted diseases; Unprotected sex

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