title: Relationship duration and mental health outcomes: findings from a 30-year longitudinal study.
abstract: BACKGROUND
  Marriage is known to be associated with improved mental health, but little research has examined whether the duration of a cohabiting relationship is associated with mental health.
  
  
  OBJECTIVE
  To examine the associations between relationship duration and mental health problems in a birth cohort of 30-year-olds.
  
  
  METHODS
  Associations between relationship duration and mental health were examined using a generalised estimating equation approach. Associations were adjusted for covariates, including prior mental health problems.
  
  
  RESULTS
  Longer relationship duration was significantly associated with lower rates of depression, suicidal behaviour and substance abuse/dependence, even after adjustment for covariates. In most cases the associations did not vary with gender. Legal relationship status (legally or de facto married) was not significantly related to mental health once due allowance was made for relationship duration.
  
  
  CONCLUSIONS
  Increasing relationship duration, but not legal relationship status, has a protective effect on mental health for men and women.
authors.affiliation: Christchurch Health and Development Study, University of Otago, Christchurch, PO Box 4345, Christchurch, New Zealand. sheree.gibb@otago.ac.nz
authors.forename: Sheree J
authors.initials: SJ
authors.lastname: Gibb
authors.forename: David M
authors.initials: DM
authors.lastname: Fergusson
authors.forename: L John
authors.initials: LJ
authors.lastname: Horwood
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002649:Child Abuse / Q000706:statistics & numerical data; D002675:Child, Preschool; D015331:Cohort Studies; D005260:Female; D006801:Humans; D007223:Infant; D007398:Interpersonal Relations; D008297:Male; D017533:Marital Status / Q000706:statistics & numerical data*; D001523:Mental Disorders / Q000453:epidemiology*; D009520:New Zealand / Q000453:epidemiology; D012959:Socioeconomic Factors; D013997:Time Factors; D055815:Young Adult