title: Influences on adolescents' decision to postpone onset of sexual intercourse: a survival analysis of virginity among youths aged 13 to 18 years.
abstract: BACKGROUND
  Previous research has focused on risk factors associated with early onset of sexual intercourse among adolescents. This study hypothesizes that protective factors identified for other health compromising behaviors are also protective against early onset of sexual intercourse. The study sample included 26,023 students in grades 7-12 (87.5% white, 52.5% male) who did not report a history of sexual abuse in a statewide survey of adolescent health in 1988.
  
  
  METHODS
  Bivariate analyses were stratified into early (13-14 years), middle (15-16 years) and late (17-18 years) adolescence and by gender. Cox proportional hazards survival analysis, stratified by gender, was used to determine risk and protective factors associated with delayed onset of sexual intercourse.
  
  
  RESULTS
  Variables showing a significant bivariate association with lower levels of sexual activity across all age groups and genders were: dual-parent families, higher socioeconomic status (SES), better school performance, greater religiosity, absence of suicidal thoughts, feeling adults or parents cared, and high parental expectations. High levels of body pride were associated with higher levels of sexual activity for all age and gender groups. In the multivariate survival analyses, variables significantly associated with delayed onset of sexual activity for both males and females included: dual-parent families, higher SES, residing in rural areas, higher school performance, concerns about the community, and higher religiosity. High parental expectations were a significant protective factor for males but not for females.
  
  
  CONCLUSIONS
  While many protective factors are not subject to intervention, the present analyses indicate that teen pregnancy prevention may be enhanced by addressing family and educational factors.
authors.affiliation: Department of Pediatrics, School of Medicine, University of Minnesota, Minneapolis 55455, USA.
authors.forename: C
authors.initials: C
authors.lastname: Lammers
authors.forename: M
authors.initials: M
authors.lastname: Ireland
authors.forename: M
authors.initials: M
authors.lastname: Resnick
authors.forename: R
authors.initials: R
authors.lastname: Blum
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior; D000328:Adult; D000704:Analysis of Variance; D003657:Decision Making; D005260:Female; D007722:Health Knowledge, Attitudes, Practice; D006801:Humans; D008297:Male; D008910:Minnesota; D011247:Pregnancy; D016016:Proportional Hazards Models; D000297:Psychology, Adolescent; D012067:Religion; D012111:Residence Characteristics; D012307:Risk Factors; D012746:Sexual Abstinence; D012959:Socioeconomic Factors; D011795:Surveys and Questionnaires; D016019:Survival Analysis