title: Pre-natal and post-natal exposure to respiratory infection and atopic diseases development: a historical cohort study.
abstract: BACKGROUND
  According to the hygiene hypothesis, infections in early life protect from allergic diseases. However, in earlier studies surrogate measures of infection rather than clinical infections were associated with decreased frequencies of atopic diseases. Exposure to infection indicating sub-clinical infection rather than clinical infection might protect from atopic diseases.
  
  
  OBJECTIVE
  to investigate whether exposure to acute respiratory infections within pregnancy and the first year of life is associated with atopic conditions at age 5-14 years and to explore when within pregnancy and the first year of life this exposure is most likely to be protective.
  
  
  METHODS
  Historical cohort study: Population level data on acute respiratory infections from the routine reporting system of the former German Democratic Republic were linked with individual data from consecutive surveys on atopic diseases in the same region (n = 4672). Statistical analyses included multivariate logistic regression analysis and polynomial distributed lag models.
  
  
  RESULTS
  High exposure to acute respiratory infection between pregnancy and age one year was associated with overall reduced odds of asthma, eczema, hay fever, atopic sensitization and total IgE. Exposure in the first 9 months of life showed the most pronounced effect. Adjusted odds ratio's for asthma, hay fever, inhalant sensitization and total IgE were statistical significantly reduced up to around half.
  
  
  CONCLUSIONS
  Exposure to respiratory infection (most likely indicating sub-clinical infection) within pregnancy and the first year of life may be protective in atopic diseases development. The post-natal period thereby seems to be particularly important.
authors.affiliation: GSF- Institut für Epidemiologie, Neuherberg, Germany. anne.zutavern@gsf.de
authors.forename: Anne
authors.initials: A
authors.lastname: Zutavern
authors.forename: Stephanie
authors.initials: S
authors.lastname: von Klot
authors.forename: Ulrike
authors.initials: U
authors.lastname: Gehring
authors.forename: Susanne
authors.initials: S
authors.lastname: Krauss-Etschmann
authors.forename: Joachim
authors.initials: J
authors.lastname: Heinrich
mesh_terms: D000293:Adolescent; D000367:Age Factors; D001249:Asthma / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D003876:Dermatitis, Atopic / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D005260:Female; D005859:Germany, East / Q000453:epidemiology; D006801:Humans; D007112:Immunity, Maternally-Acquired; D007223:Infant; D007231:Infant, Newborn; D016015:Logistic Models; D008297:Male; D011247:Pregnancy; D011251:Pregnancy Complications, Infectious / Q000453:epidemiology / Q000276:immunology*; D015995:Prevalence; D012141:Respiratory Tract Infections / Q000453:epidemiology / Q000276:immunology*; D006255:Rhinitis, Allergic, Seasonal / Q000453:epidemiology* / Q000276:immunology / Q000517:prevention & control; D011795:Surveys and Questionnaires