title: Association of Age at Menarche and Menstrual Characteristics with Adult Onset Asthma among Reproductive Age Women.
abstract: BACKGROUND
  Observations of increasing asthma incidence, decreasing age at menarche, and common risk factors have led investigators to hypothesize potential associations of age at menarche or menstrual characteristics with incidence of adult onset asthma. We evaluated these associations among reproductive age women.
  
  
  METHODS
  Study participants were selected from among women enrolled in a pregnancy cohort study. Information on age at menarche, menstrual characteristics, and history of asthma was collected using interviewer-administered questionnaires. Adult onset asthma was defined as asthma first diagnosed after onset of menarche. Women who had no information on asthma and menstrual history and those who were diagnosed with asthma before menarche were excluded. A total of 3,461 women comprised the analytic population. Logistic regression was used to estimate adjusted relative risk (aRR) and 95% confidence intervals (95% CI) relating age at menarche and menstrual characteristics with adult onset asthma.
  
  
  RESULTS
  Mean age at menarche was 12.8 years (standard deviation=1.46). Among study participants, 7.5% were diagnosed with asthma after the onset of menarche. After controlling for potential confounders (age, race, body mass index, and socio-economic status), women who had early menarche (<12 years old) had 60% higher risk of being diagnosed with adult onset asthma as compared with women who did not have early menarche (≥ 12 years old) (aRR= 1.59, 95% CI 1.19 - 2.13). Menstrual irregularities or abnormal (short or long) cycle length were not associated with risk of adult onset asthma. In addition, no significant interaction was observed between age at menarche or menstrual characteristics with body mass index or physical activity (in adolescence) in relation to adult onset asthma.
  
  
  CONCLUSIONS
  Early menarche is associated with a higher risk of developing adult onset asthma among reproductive age women. Mechanisms for this association are potential areas of future research.
authors.affiliation: Center for Perinatal Studies, Swedish Medical Center, Seattle, WA ; Department of Epidemiology, University of Washington, Seattle, WA.
authors.forename: Neway G
authors.initials: NG
authors.lastname: Fida
authors.affiliation: Department of Epidemiology, Harvard School of Public Health, Boston, MA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.affiliation: Center for Perinatal Studies, Swedish Medical Center, Seattle, WA ; Department of Epidemiology, University of Washington, Seattle, WA.
authors.forename: Daniel A
authors.initials: DA
authors.lastname: Enquobahrie