title: [Parity and menarche as risk factors of osteoporosis in postmenopausal Mexican women].
abstract: BACKGROUND
  At the moment the studies lead at world-wide level and even in our country have thrown discrepant results about the relation between osteoporosis, parity and age of menarche.
  
  
  OBJECTIVE
  To investigate the relation of osteoporosis in postmenopausal Mexican women with multiparity and age of menarche.
  
  
  METHODS
  A retrospective and analytical cross-sectional study, with a non-probabilistic sampling technique in women rightful claimants of the IMSS, San Luis Potosi. In all of them the bone mineral density was measured with X-ray dual absorptiometry in the distal forearm. Reproductive history and age of menarche were obtained by the addition of these items to the previously validated Albrand questionnaire. Women were divided into groups according to the number of pregnancies in: normal parity (0 to 3 childbirths) conformed by 112 patients (46%) and multiparity (> or = 4 pregnancies), 131 women (54%). In relation to menarche with an average of 12.98 years, from this number we divided them in: early menarche (< 13 yrs) and late menarche (> or = 13 yrs).
  
  
  RESULTS
  243 women were studied, with an average of age of 55.92, rank 31 to 80 years. Using the criteria of the World Health Organization, 18% of postmenopausal women had osteoporosis, 39% had osteopenia and 43% had bone normality. No association was found between the number of pregnancies and osteoporosis. Additionally we observed that the women who had four or more children were older than the other women, average 57.42 against 54.16. Also there was significant negative correlation (r = -0.43) between age and densitometry. We found that an age greater to 13 years in the appearance of the menarche was related to osteoporosis (OR 4.46, p: 0.035).
  
  
  CONCLUSIONS
  In postmenopausal women a menarche older than 13 years is a risk factor for osteoporosis.
authors.affiliation: Instituto Mexicano del Seguro Social, San Luis Potosí, SLP, México. miguel.mendozaro@imss.gob.mx
authors.forename: Miguel Angel
authors.initials: MA
authors.lastname: Mendoza-Romo
authors.forename: María Cleofas
authors.initials: MC
authors.lastname: Ramírez-Arriola
authors.forename: José Fernando
authors.initials: JF
authors.lastname: Velasco-Chávez
authors.forename: José Guillermo
authors.initials: JG
authors.lastname: Rivera-Martínez
authors.forename: Rafael Natividad
authors.initials: RN
authors.lastname: Nieva-de Jesús
authors.forename: Luis Alvaro
authors.initials: LA
authors.lastname: Valdez-Jiménez
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008572:Menarche; D008800:Mexico; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000453:epidemiology*; D010298:Parity; D017698:Postmenopause; D012189:Retrospective Studies; D012307:Risk Factors