title: Relation between phase of the menstrual cycle and asthma presentations in the emergency department.
abstract: BACKGROUND
  The phase of the menstrual cycle is thought to influence the course of asthma in women. One recent study reported a large increase in exacerbations during the perimenstrual phase, while another found a preovulatory increase. A study was undertaken to determine the relation between phase of the menstrual cycle and acute asthma in patients presenting to the emergency department (ED).
  
  
  METHODS
  All women aged 18-54 years presenting with a diagnosis of acute asthma exacerbation were considered for enrollment in the study. Women who were pregnant, postmenopausal, following hysterectomy, with a >28 day menstrual cycle or incomplete reproductive history were excluded. The 792 eligible women were classified by menstrual phase based on both date of symptom onset and date of ED visit.
  
  
  RESULTS
  When classified by date of symptom onset, 28% were preovulatory (days 5 to 11), 25% were periovulatory (days 12 to 18), 21% were postovulatory (days 19 to 25), and 27% were perimenstrual (days 26 to 4; p = 0.03). When classified by date of ED visit, 28% were preovulatory, 22% were periovulatory, 22% were postovulatory, and 27% were perimenstrual (p = 0.004). Using either approach, there were no significant differences in demographic factors or in asthma severity of women in the various menstrual phase groups.
  
  
  CONCLUSIONS
  Acute asthma exacerbations do not markedly increase during the perimenstrual phase. The results support the suggestion that both preovulatory and perimenstrual phases are actual triggers of asthma exacerbation in some women, or that these two phases serve as "co-factors" that worsen other recognised triggers of acute asthma.
authors.affiliation: Department of Emergency Medicine, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA. brennerbarry@uams.edu
authors.forename: B E
authors.initials: BE
authors.lastname: Brenner
authors.forename: T M
authors.initials: TM
authors.lastname: Holmes
authors.forename: B
authors.initials: B
authors.lastname: Mazal
authors.forename: C A
authors.initials: CA
authors.lastname: Camargo
mesh_terms: D000208:Acute Disease; D000293:Adolescent; D000328:Adult; D001249:Asthma / Q000209:etiology* / Q000628:therapy; D004636:Emergency Service, Hospital / Q000706:statistics & numerical data*; D005260:Female; D006801:Humans; D008597:Menstrual Cycle / Q000502:physiology*; D008875:Middle Aged; D010342:Patient Acceptance of Health Care / Q000706:statistics & numerical data*; D011446:Prospective Studies