title: Early menstrual characteristics associated with subsequent diagnosis of endometriosis.
abstract: OBJECTIVE
  The aim of this study was to investigate the association between early menstrual characteristics, before symptom onset, and later diagnosis of endometriosis.
  
  
  METHODS
  This was a case-control study of 268 Australian women with surgically confirmed moderate-to-severe endometriosis (cases) and 244 women without endometriosis (controls). Early menstrual cycle characteristics, before age at symptom onset, were analyzed.
  
  
  RESULTS
  Menarche after age 14 years was strongly and inversely associated with endometriosis (odds ratio, 0.3; 95% confidence interval, 0.1-0.6). A history of dysmenorrhea was associated with subsequent endometriosis (odds ratio, 2.6; 95% confidence interval, 1.1-6.2). Despite a suggestive trend, shorter menstrual cycle length was not associated with endometriosis. Duration of natural menstruation and heaviness of flow were not associated with subsequent risk of endometriosis; neither was the reported type of sanitary protection used nor history of sexual intercourse during menstruation.
  
  
  CONCLUSIONS
  There is a decreased risk of endometriosis with late age at menarche and an increased risk in women who report an early history of dysmenorrhea.
authors.affiliation: Center for Military and Veterans' Health, The University of Queensland, Brisbane, Australia. s.treloar@uq.edu.au
authors.forename: Susan A
authors.initials: SA
authors.lastname: Treloar
authors.forename: Tanya A
authors.initials: TA
authors.lastname: Bell
authors.forename: Christina M
authors.initials: CM
authors.lastname: Nagle
authors.forename: David M
authors.initials: DM
authors.lastname: Purdie
authors.forename: Adèle C
authors.initials: AC
authors.lastname: Green
mesh_terms: D000293:Adolescent; D000328:Adult; D000367:Age Factors; D017668:Age of Onset; D001315:Australia; D016022:Case-Control Studies; D002648:Child; D004412:Dysmenorrhea / Q000150:complications* / Q000175:diagnosis; D004715:Endometriosis / Q000150:complications* / Q000175:diagnosis*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008572:Menarche / Q000502:physiology; D008597:Menstrual Cycle / Q000502:physiology; D008875:Middle Aged; D016017:Odds Ratio; D011795:Surveys and Questionnaires