title: Maternal atopy and changes in parity.
abstract: BACKGROUND
  Atopic women tend to have fewer children, although atopy may favour conception.
  
  
  OBJECTIVE
  To assess whether atopy is associated with the number of new births and whether changes in parity are associated with a change in atopy in a cohort of young women.
  
  
  METHODS
  Women had atopy (defined as the presence of serum-specific IgE against common aeroallergens) measured in the European Community Respiratory Health Study during the years 1991--92 (n=4580). About 9 years later, 2844 (62.1%) were recontacted and 2414 (52.7%) had atopy measured again.
  
  
  RESULTS
  Atopic women had fewer children at baseline than non-atopic women but the association disappeared at the end of the follow-up. Atopy tended to increase parity during the follow-up, but in a non-statistically significant way (relative risk=1.08; 0.86-1.35, after adjusting for number of children at baseline, age, length of follow-up, education or social class). Prevalence of atopy during the follow-up changed by the same magnitude whatever the birth cohort and the change in the number of children (P for interaction >0.7).
  
  
  CONCLUSIONS
  Atopic women did not have a significantly higher fertility rate but they may postpone having their first child compared with non-atopic women. We are unable to confirm the hypothesis that atopy in women may decrease with successive pregnancies.
authors.affiliation: Unitat de Recerca Respiratoria i Ambiental, Institut Municipal d'Investigació Mèdica, Barcelona, Spain.
authors.forename: J
authors.initials: J
authors.lastname: Sunyer
authors.forename: J M
authors.initials: JM
authors.lastname: Antó
authors.forename: E
authors.initials: E
authors.lastname: Plana
authors.forename: C
authors.initials: C
authors.lastname: Janson
authors.forename: D
authors.initials: D
authors.lastname: Jarvis
authors.forename: S
authors.initials: S
authors.lastname: Kony
authors.forename: E R
authors.initials: ER
authors.lastname: Omenaas
authors.forename: C
authors.initials: C
authors.lastname: Svanes
authors.forename: M
authors.initials: M
authors.lastname: Wjst
authors.forename: B
authors.initials: B
authors.lastname: Leynaert
mesh_terms: D000328:Adult; D000485:Allergens / Q000276:immunology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000276:immunology*; D007108:Immune Tolerance / Q000276:immunology; D007073:Immunoglobulin E / Q000097:blood; D008423:Maternal Age; D009035:Mothers; D010298:Parity; D011247:Pregnancy; D015995:Prevalence; D012307:Risk Factors; D012959:Socioeconomic Factors
chemical_list: D000485:Allergens; D007073:Immunoglobulin E