title: Do perceptions of friends' behaviors affect age at first sex? Evidence from Cebu, Philippines.
abstract: OBJECTIVE
  To explore the effect of perceptions of friends' romantic and physical behaviors on adolescent sexual behavior and the relative influence of friends' sexual behaviors and maternal attitudes on age at first sex.
  
  
  METHODS
  Using longitudinal data collected from 1943 adolescents who have never had sex at baseline in Cebu, Philippines, logistic regression assessed whether adolescents' perceptions of friends' sexual behaviors, measured at ages 14 to 16 years, were associated with age at first intercourse. Survival analysis assessed the hazard of having first intercourse by ages 17 to 19 years. Final models adjusted for sociodemographics, mothers'/caretakers' disapproval of premarital sex, living with a caretaker, and the adolescents' own behaviors at baseline.
  
  
  RESULTS
  Boys and girls, who at ages 14 to 16 years, perceived that their friends had ever had boyfriends/girlfriends, dated, held hands, kissed, petted or had sex were significantly more likely to have experienced that behavior by ages 17 to 19 years. For each additional behavior an adolescent perceived his or her friends to have experienced, the hazard of having sex at a younger age increased by 1.15 (p = .02) among boys and 1.19 (p < .002) among girls, after adjusting for mothers'/caretakers' disapproval of premarital sex and other factors.
  
  
  CONCLUSIONS
  These results demonstrate the important role of peers in light of competing influences in adolescents' lives. They provide support for asking at early ages what romantic and physical behaviors adolescents think their friends have experienced. Interventions can use such information to better prepare adolescents to make responsible and informed decisions about sexuality.
authors.affiliation: Department of Population and Family Health Sciences, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland 21202, USA. ushma@jhu.edu
authors.forename: Ushma D
authors.initials: UD
authors.lastname: Upadhyay
authors.forename: Michelle J
authors.initials: MJ
authors.lastname: Hindin
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D000328:Adult; D003075:Coitus; D003625:Data Collection; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D010287:Parent-Child Relations; D010379:Peer Group; D010679:Philippines