title: Early sexual initiation: the role of peer norms.
abstract: OBJECTIVE
  To elucidate which components of peer norms influence the process of sexual initiation for young adolescents. Design. Prospective cohort study. Setting. Fourteen elementary and middle schools in an urban public school district. Participants. The 1389 sixth-grade students who completed the questionnaire at the beginning (time 1) and at the end (time 2) of the school year comprise the study sample. Mean age at time 1 was 11.7 years.
  
  
  RESULTS
  Of students entering the sixth grade, 30% (n = 416) reported having already initiated sexual intercourse, 5% (n = 74) reported initiating sexual intercourse during the sixth-grade school year (initiated group), and 63% (n = 873) reported not having initiated sexual intercourse by the end of the sixth-grade school year (never group). Demographic comparisons revealed that students in the initiated group were significantly more likely than students in the never group to be older (11.9 years vs 11.6 years), male (58% vs 37%), African-American (70% vs 51%), attending a poorer school (87% vs 85%), and living in an area with a high proportion of single-parent families (45% vs 41%). Self-reports and reports of peers' participation in nonsexual risk behaviors were more common for students in the initiated group. Students in the initiated group were more likely than students in the never group to perceive: 1) a high prevalence of sexual initiation among peers; 2) social gains associated with early sexual intercourse; and 3) younger age of peers' sexual initiation. Students in the never group were more likely to believe that sexually-experienced 12-year-old boys would be negatively stigmatized compared with students in the initiated group. Three predictive models were developed to test the relationship between peer norms and the process of initiation. These models demonstrate that the strongest predictor of sexual initiation in sixth grade is having high intention to do so at the beginning of sixth grade. The strongest predictor of high intention is belief that most friends have already had sexual intercourse. Perceptions of social gain and stigma for sexually-experienced 12-year-old boys act independently of intention to decrease risk of early sexual initiation.
  
  
  CONCLUSIONS
  Early sexual intercourse is not an unplanned experience for many teens. Decisions about initiation are strongly bound to social context with peers playing an important role in creating a sense of normative behavior. Specific components of peer norms impact the process of sexual initiation in both positive and negative ways. Interventions aimed at delaying the onset of sexual initiation need to focus on cohort norms as well as on an individual's perceptions and behaviors.
authors.affiliation: Section of Adolescent Medicine, Division of General Pediatrics, Children's Hospital of Philadelphia, Philadelphia, Pennsylvania, USA.
authors.forename: S B
authors.initials: SB
authors.lastname: Kinsman
authors.forename: D
authors.initials: D
authors.lastname: Romer
authors.forename: F F
authors.initials: FF
authors.lastname: Furstenberg
authors.forename: D F
authors.initials: DF
authors.lastname: Schwarz
mesh_terms: D000367:Age Factors; D002648:Child; D002652:Child Behavior; D003075:Coitus / Q000523:psychology*; D003625:Data Collection; D005260:Female; D006801:Humans; D008297:Male; D008960:Models, Psychological; D010379:Peer Group; D015143:Philadelphia; D011446:Prospective Studies; D012309:Risk-Taking; D012736:Sex Education; D012737:Sex Factors; D012725:Sexual Behavior / Q000523:psychology / Q000706:statistics & numerical data; D012925:Social Conformity; D012945:Social Values; D012959:Socioeconomic Factors; D014505:Urban Population