title: Early Sexual Intercourse: Prospective Associations with Adolescents Physical Activity and Screen Time.
abstract: OBJECTIVE
  To assess the prospective associations of physical activity behaviors and screen time with early sexual intercourse initiation (i.e., before 15 years) in a large sample of adolescents.
  
  
  METHODS
  We used two waves of data from the Rotterdam Youth Monitor, a longitudinal study conducted in the Netherlands. The analysis sample consisted of 2,141 adolescents aged 12 to 14 years (mean age at baseline = 12.2 years, SD = 0.43). Physical activity (e.g., sports outside school), screen time (e.g., computer use), and early sexual intercourse initiation were assessed by means of self-report questionnaires. Logistic regression models were tested to assess the associations of physical activity behaviors and screen time (separately and simultaneously) with early sexual intercourse initiation, controlling for confounders (i.e., socio-demographics and substance use). Interaction effects with gender were tested to assess whether these associations differed significantly between boys and girls.
  
  
  RESULTS
  The only physical activity behavior that was a significant predictor of early sexual intercourse initiation was sports club membership. Adolescent boys and girls who were members of a sports club) were more likely to have had early sex (OR = 2.17; 95% CI = 1.33, 3.56. Significant gender interaction effects indicated that boys who watched TV ≥2 hours/day (OR = 2.00; 95% CI = 1.08, 3.68) and girls who used the computer ≥2 hours/day (OR = 3.92; 95% CI = 1.76, 8.69) were also significantly more likely to have engaged in early sex.
  
  
  CONCLUSIONS
  These findings have implications for professionals in general pediatric healthcare, sexual health educators, policy makers, and parents, who should be aware of these possible prospective links between sports club membership, TV watching (for boys), and computer use (for girls), and early sexual intercourse initiation. However, continued research on determinants of adolescents' early sexual initiation is needed to further contribute to the strategies for improving adolescents' healthy sexual development and behaviors.
authors: Department of Public Health, Erasmus University Medical Center, University of Rotterdam, Rotterdam, the Netherlands.
authors: Raquel
authors: http://orcid.org/0000-0001-7895-0936
authors: R
authors: Nogueira Avelar E Silva
authors: Department of Public Health, Erasmus University Medical Center, University of Rotterdam, Rotterdam, the Netherlands.
authors: Anne
authors: A
authors: Wijtzes
authors: Research Institute of Child Development and Education (Research Priority Area YIELD), University of Amsterdam, Amsterdam, the Netherlands.
authors: Daphne
authors: D
authors: van de Bongardt
authors: Department of Research and Business Intelligence, Municipality of Rotterdam, Rotterdam, the Netherlands.
authors: Petra
authors: P
authors: van de Looij-Jansen
authors: Department of Public Health, Erasmus University Medical Center, University of Rotterdam, Rotterdam, the Netherlands.
authors: Rienke
authors: R
authors: Bannink
authors: Department of Public Health, Erasmus University Medical Center, University of Rotterdam, Rotterdam, the Netherlands.
authors: Hein
authors: H
authors: Raat
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology*; D002648:Child; D003075:Coitus / Q000523:psychology*; D005260:Female; D006801:Humans; D020407:Internet; D008137:Longitudinal Studies; D008297:Male; D009426:Netherlands; D011446:Prospective Studies; D011606:Psychosexual Development / Q000502:physiology*; D012309:Risk-Taking; D012931:Social Environment; D013177:Sports; D011795:Surveys and Questionnaires; D013690:Television