title: When they break up and get back together:  length of adolescent romantic relationships and partner concurrency.
abstract: BACKGROUND
  Sex partner concurrency is an important risk factor for sexually transmitted infection transmission. Understanding how adolescents conceptualize the length of their relationships when they break up and get back together is essential to the assessment of concurrency.
  
  
  METHODS
  A prospective cohort of 392 late adolescents and emerging adults, aged 14 to 19 years at baseline, were recruited from 2 clinics in Baltimore, MD and interviewed semiannually for 3 years. At each interview, participants were asked to report on all of their sexual partners in the previous 6 months, the length of relationship, and whether they thought their partner had other sex partners. For relationships that had broken up and gotten back together, reports of length of the relationship were compared before and after the breakup. Random effects logistic regression was used to examine the association between length of relationship and both breakup and partner concurrency.
  
  
  RESULTS
  For relationships that ended and subsequently got back together, participants considered the length of relationship to include the period when they were broken up. Longer relationships were at increased odds of both having broken up and gotten back together (odds ratio [OR] = 1.04, 95% confidence interval [CI]: 1.02, 1.05) and of partner concurrency (OR = 1.03, 95% CI: 1.02, 1.04). The magnitude of the odds of concurrency was greater for relationships that had broken up and gotten back together (OR = 1.07, 95% CI: 1.02, 1.11).
  
  
  CONCLUSIONS
  Findings from this study emphasize the need for an improved understanding of the association between the temporal dynamics of late adolescent and emerging adult romantic relationships and concurrency.
authors.affiliation: Department of Pediatrics, Center for Child and Community Health Research, Johns Hopkins University School of Medicine, Baltimore, MD, USA. pmatson@jhmi.edu
authors.forename: Pamela Ann
authors.initials: PA
authors.lastname: Matson
authors.forename: Shang-en
authors.initials: SE
authors.lastname: Chung
authors.forename: Jonathan Mark
authors.initials: JM
authors.lastname: Ellen
mesh_terms: D000293:Adolescent; D000294:Adolescent Behavior / Q000523:psychology; D001741:Black or African American / Q000706:statistics & numerical data; D015142:Baltimore / Q000453:epidemiology; D015331:Cohort Studies; D004644:Emotions; D005260:Female; D006801:Humans; D007398:Interpersonal Relations; D016015:Logistic Models; D008297:Male; D011446:Prospective Studies; D012725:Sexual Behavior / Q000523:psychology / Q000706:statistics & numerical data; D012747:Sexual Partners; D012749:Sexually Transmitted Diseases / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control*; D044465:White People / Q000706:statistics & numerical data; D055815:Young Adult