title: Sexual behavior among high school students in Brazil: alcohol consumption and legal and illegal drug use associated with unprotected sex.
abstract: OBJECTIVE
  Alcohol and other drug use appears to reduce decision-making ability and increase the risk of unsafe sex, leading to possible unplanned pregnancies, sexually transmitted diseases/human immunodeficiency virus/HIV transmission, and multiple sexual partners. This study aimed to test the hypothesis that risky sexual behaviors among adolescents are associated with legal and illegal drug use.
  
  
  METHODS
  A national cross-sectional survey of 17,371 high-school students was conducted in 2010. Students were selected from 789 public and private schools in each of the 27 Brazilian state capitals by a multistage probabilistic sampling method and answered a self-report questionnaire. Weighted data were analyzed through basic contingency tables and logistic regressions testing for differences in condom use among adolescents who were sexually active during the past month.
  
  
  RESULTS
  Approximately one third of the high school students had engaged in sexual intercourse in the month prior to the survey, and nearly half of these respondents had not used a condom. While overall sexual intercourse was more prevalent among boys, unsafe sexual intercourse was more prevalent among girls. Furthermore, a lower socioeconomic status was directly associated with non-condom use, while binge drinking and illegal drug use were independently associated with unsafe sexual intercourse.
  
  
  CONCLUSIONS
  Adolescent alcohol and drug use were associated with unsafe sexual practices. School prevention programs must include drug use and sexuality topics simultaneously because both risk-taking behaviors occur simultaneously.
authors.affiliation: Escola Paulista de Medicina, Universidade Federal de São Paulo, Brazilian Center of Information of Psychotropic Drugs, Department of Preventive Medicine, São Paulo/SP, Brazil. zila.sanchez@gmail.com
authors.forename: Zila M
authors.initials: ZM
authors.lastname: Sanchez
authors.forename: Solange A
authors.initials: SA
authors.lastname: Nappo
authors.forename: Joselaine I
authors.initials: JI
authors.lastname: Cruz
authors.forename: Elisaldo A
authors.initials: EA
authors.lastname: Carlini
authors.forename: Claudia M
authors.initials: CM
authors.lastname: Carlini
authors.forename: Silvia S
authors.initials: SS
authors.lastname: Martins
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D017677:Age Distribution; D000428:Alcohol Drinking / Q000453:epidemiology*; D001938:Brazil / Q000453:epidemiology; D017280:Condoms / Q000706:statistics & numerical data; D004812:Epidemiologic Methods; D005260:Female; D006801:Humans; D008297:Male; D012309:Risk-Taking; D012574:Schools; D017678:Sex Distribution; D012725:Sexual Behavior / Q000706:statistics & numerical data*; D012959:Socioeconomic Factors; D013334:Students / Q000706:statistics & numerical data*; D019966:Substance-Related Disorders / Q000453:epidemiology*; D047568:Unsafe Sex / Q000706:statistics & numerical data