title: Age at menarche, age at menopause and duration of fertility as risk factors for osteoporosis.
abstract: OBJECTIVE
  To investigate the relationship of osteopenia and osteoporosis in apparently healthy postmenopausal patients with age at menarche, age at menopause and duration of fertility.
  
  
  METHODS
  One hundred and twenty-four apparently healthy Greek postmenopausal women underwent spinal and hip X-ray absorptiometry scans. Among them, 47 were classified as normal (control group), 52 as osteopenic, and 25 as having osteoporosis. These groups were compared according to their age at menarche (three subgroups of 10-12, 13 and 14-16 years old), at menopause (three subgroups of 40-45, 46-50 and > or = 51 years old) and duration of fertility (four subgroups of < or = 30, 31-35, 36-40 and 41-45 years).
  
  
  RESULTS
  The groups were not found to differ statistically according to age and age at menarche. However, decreased bone mineral density was found in patients with duration of fertility not exceeding 30 years (p = 0.034) and age at menopause less than 45 years (p = 0.034). No association was found between bone mineral density in Greek postmenopausal women and either number of live births or lactation.
  
  
  CONCLUSIONS
  In postmenopausal females, the cumulative exposure to endogenous estrogens, measured as years of menstruation, seems to be a significant protective factor against the development of postmenopausal osteoporosis. Age at menopause between 40 and 45 years, but not age at menarche, correlated with low bone mineral density in postmenopausal females.
authors.affiliation: Department of Nuclear Medicine, University Hospital of Ioannina, Ioannina, Greece.
authors.forename: C
authors.initials: C
authors.lastname: Sioka
authors.forename: A
authors.initials: A
authors.lastname: Fotopoulos
authors.forename: A
authors.initials: A
authors.lastname: Georgiou
authors.forename: X
authors.initials: X
authors.lastname: Xourgia
authors.forename: A
authors.initials: A
authors.lastname: Papadopoulos
authors.forename: J A
authors.initials: JA
authors.lastname: Kalef-Ezra
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D015519:Bone Density; D005260:Female; D005269:Femur; D005298:Fertility / Q000502:physiology*; D006801:Humans; D007774:Lactation; D008159:Lumbar Vertebrae; D008572:Menarche / Q000502:physiology*; D008593:Menopause / Q000502:physiology*; D008875:Middle Aged; D010024:Osteoporosis / Q000453:epidemiology*; D011247:Pregnancy; D018873:Pregnancy Rate; D012189:Retrospective Studies; D012307:Risk Factors; D013997:Time Factors