title: Young age at first intercourse and subsequent risk-taking behaviour: An epidemiological study of more than 20,000 Danish men from the general population.
abstract: OBJECTIVE
  First intercourse at the age of 14 years or younger is usually considered high-risk behaviour for sexually transmitted infections (STIs). It has been linked to other types of risky behaviour in women, while conflicting results have been obtained for men. The aim of the study was to estimate the prevalence of first intercourse at a young age in various birth cohorts of men and to determine any association with later risky behaviour.
  
  
  METHODS
  We studied 22,979 randomly selected men aged 18-45 years from the Danish general male population who responded to a self-administered questionnaire. Multiple sexual partners over a lifetime, multiple new sexual partners within the past 6 months, intercourse with a commercial sex worker, having an STI, binge drinking and current smoking were considered risky behaviour.
  
  
  RESULTS
  First intercourse at the age of 14 years or younger was more prevalent in younger (14%) than in older (10%) birth cohorts and among men with shorter schooling. Young age at sexual debut was associated with a more than twofold increase in the risks for subsequent risky behaviour.
  
  
  CONCLUSIONS
  More than 10% of Danish men first had sex at an early age, and this was closely related to subsequent risk-taking behaviour.
authors.affiliation: Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Nina
authors.initials: N
authors.lastname: Buttmann
authors.affiliation: Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Ann
authors.initials: A
authors.lastname: Nielsen
authors.affiliation: Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Christian
authors.initials: C
authors.lastname: Munk
authors.affiliation: Statistics, Bioinformatics and Registries, Danish Cancer Society Research Center, Copenhagen, Denmark.
authors.forename: Kirsten
authors.initials: K
authors.lastname: Frederiksen
authors.affiliation: Merck Research Laboratories, North Wales, PA, USA.
authors.forename: Kai-Li
authors.initials: KL
authors.lastname: Liaw
authors.affiliation: Virus, Lifestyle and Genes, Danish Cancer Society Research Center, Copenhagen, Denmark Department of Gynaecology, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark susanne@cancer.dk.
authors.forename: Susanne K
authors.initials: SK
authors.lastname: Kjaer
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D063425:Binge Drinking / Q000453:epidemiology; D015331:Cohort Studies; D003075:Coitus; D003718:Denmark / Q000453:epidemiology; D006801:Humans; D008297:Male; D008875:Middle Aged; D018570:Risk Assessment; D012309:Risk-Taking; D011477:Sex Work; D012747:Sexual Partners; D012749:Sexually Transmitted Diseases / Q000453:epidemiology; D012907:Smoking / Q000453:epidemiology; D011795:Surveys and Questionnaires; D055815:Young Adult
keywords: Sexual behaviour; epidemiology; male; risk-taking behaviour; sexual debut