title: Physical activity and age at menopause: the Nord-Trøndelag population-based health study.
abstract: BACKGROUND
  Age at menopause may affect women's subsequent morbidity and mortality. In contrast to numerous other health outcomes, little is known about the possible effects of physical activity on age at menopause.
  
  
  OBJECTIVE
  To assess the relationship between leisure-time physical activity and age at menopause.
  
  
  METHODS
  Premenopausal women participating in a population-based health survey (HUNT 2) conducted in the county of Nord-Trøndelag, Norway reported their physical activity in the period of 1995-1997. Age at menopause was reported during 2006-2008 (HUNT 3). Cox proportional hazards models were used to estimate hazard ratios for menopause and logistic regression to estimate odds ratios for early menopause, with 95% confidence intervals, adjusting for age at menarche, parity, use of oral contraceptives prior to the 6 months preceding participation in HUNT 2, symptoms of depression, smoking status, and education.
  
  
  RESULTS
  Women aged 40-49 years at baseline had lower hazard ratios for menopause when participating in any light leisure-time physical activity compared with no activity (p < 0.05) and similar results were observed in 19-39-year-olds. In 50-59-year-old women, the results varied greatly and did not reach statistical significance.
  
  
  CONCLUSIONS
  The effects of leisure-time physical activity on age at menopause may be age-dependent. We found indications of earlier menopause for the least active women aged 19-49 years at baseline.
authors.affiliation: Department of Human Movement Science, Faculty of Social Sciences and Technology Management, Norwegian University of Science and Technology, Trondheim, Norway.
authors.forename: S L
authors.initials: SL
authors.lastname: Gudmundsdottir
authors.forename: W D
authors.initials: WD
authors.lastname: Flanders
authors.forename: L B
authors.initials: LB
authors.lastname: Augestad
mesh_terms: D000328:Adult; D000367:Age Factors; D016001:Confidence Intervals; D005260:Female; D006306:Health Surveys; D006801:Humans; D053208:Kaplan-Meier Estimate; D016015:Logistic Models; D008593:Menopause; D008875:Middle Aged; D009043:Motor Activity / Q000502:physiology*; D009664:Norway; D016017:Odds Ratio; D016016:Proportional Hazards Models; D055815:Young Adult