title: Maternal atopy and parity.
abstract: BACKGROUND
  Family size and high birth order were related to the prevalence of hayfever and positive skin prick test. However, this association may be explained by maternal atopy. We examined the relationship between maternal atopy and the number of offspring in three European cohorts of pregnant women.
  
  
  METHODS
  The mothers and their children (n = 1487) were recruited for the Asthma Multi-centre Infants Cohort Study (AMICS). The three concurrent cohorts (Ashford, Kent (UK); Menorca island (Spain) and Barcelona city (Spain) followed the same research protocol. Maternal and paternal atopy was identified by skin prick tests at different times at the three centres.
  
  
  RESULTS
  Maternal atopy was inversely related to the number of offspring, an association which occurred in each of the three cohorts and remained when atopy was defined separately for individual allergens (a positive response to testing with either Der p 1 or grass pollen) and which was not confounded by maternal age, smoking nor social class (the adjusted odds ratios were 0.71, 0.79 and 0.26 for increasing number of offspring, P = 0.002). Neither maternal asthma (P = 0.43) nor paternal atopy (P = 0.58) were associated with the number of offspring. Maternal atopy was not related to reproductive outcomes.
  
  
  CONCLUSIONS
  The association between maternal atopy and parity challenges the role of family size on child atopy, which should be studied in other populations.
authors.affiliation: Unitat de Recerca Respiratòria i Ambiental, Institut Municipal Investigació Mèdica , Barcelona, Catalonia, Spain. jsunyer@imim.es
authors.forename: J
authors.initials: J
authors.lastname: Sunyer
authors.forename: J M
authors.initials: JM
authors.lastname: Antó
authors.forename: J
authors.initials: J
authors.lastname: Harris
authors.forename: M
authors.initials: M
authors.lastname: Torrent
authors.forename: O
authors.initials: O
authors.lastname: Vall
authors.forename: P
authors.initials: P
authors.lastname: Cullinan
authors.forename: A
authors.initials: A
authors.lastname: Newman-Taylor
mesh_terms: D000328:Adult; D000485:Allergens / Q000009:adverse effects; D000818:Animals; D039741:Antigens, Dermatophagoides; D001249:Asthma / Q000453:epidemiology / Q000209:etiology; D002415:Cats; D015331:Cohort Studies; D005191:Family Characteristics; D005192:Family Health; D005260:Female; D006023:Glycoproteins / Q000009:adverse effects; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology* / Q000209:etiology*; D008429:Maternal Welfare; D010298:Parity / Q000235:genetics*; D011058:Pollen / Q000009:adverse effects; D011247:Pregnancy; D011248:Pregnancy Complications / Q000276:immunology*; D015995:Prevalence; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology / Q000209:etiology; D012907:Smoking / Q000009:adverse effects; D013030:Spain / Q000453:epidemiology; D006113:United Kingdom / Q000453:epidemiology
chemical_list: D000485:Allergens; D039741:Antigens, Dermatophagoides; D006023:Glycoproteins