title: Antibiotics in the first week of life is a risk factor for allergic rhinitis at school age.
abstract: BACKGROUND
  Heredity as well as external factors influences the development of allergic rhinitis. The aim of this study was to analyse early risk factors and protective factors for allergic rhinitis at school age.
  
  
  METHODS
  This is a prospective, longitudinal study of children born in western Sweden in 2003 where 50% of the birth cohort was randomly selected. The parents answered questionnaires at 6 months, 12 months, 4.5 yr and 8 yr. At 8 yr, 5044 questionnaires were distributed. Of these, 4051 responded, that is, 80.3%. Current allergic rhinitis was defined as symptoms and use of medication during the past 12 months.
  
  
  RESULTS
  Current allergic rhinitis at 8 yr was reported by 10.9%. Mean onset age was 5.7 yr, and 61.9% were boys. In a multivariate analysis, antibiotics in the first week of life increased the risk of allergic rhinitis (adjusted odds ratio 1.75, 95% confidence interval (1.03, 2.97)). Increased risk was also seen with parental allergic rhinitis (aOR 2.73 (2.12, 3.52)), food allergy first year (aOR 2.45 (1.61, 3.73)), eczema first year (aOR 1.97 (1.50, 2.59)) and male gender (aOR 1.35 (1.05, 1.74)). Living on a farm at 4.5 yr reduced the risk (aOR 0.31 (0.13, 0.78)).
  
  
  CONCLUSIONS
  Antibiotics in the first week of life increased the risk of allergic rhinitis at school age, while living on a farm at preschool age reduced the risk. Both findings are compatible with the hygiene hypothesis.
authors.affiliation: Department of Paediatrics, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Bernt
authors.initials: B
authors.lastname: Alm
authors.forename: Emma
authors.initials: E
authors.lastname: Goksör
authors.forename: Rolf
authors.initials: R
authors.lastname: Pettersson
authors.forename: Per
authors.initials: P
authors.lastname: Möllborg
authors.forename: Laslo
authors.initials: L
authors.lastname: Erdes
authors.forename: Petra
authors.initials: P
authors.lastname: Loid
authors.forename: Nils
authors.initials: N
authors.lastname: Aberg
authors.forename: Göran
authors.initials: G
authors.lastname: Wennergren
mesh_terms: D000900:Anti-Bacterial Agents / Q000009:adverse effects*; D002648:Child; D005260:Female; D006801:Humans; D007231:Infant, Newborn; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D065631:Rhinitis, Allergic / Q000453:epidemiology*; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology
chemical_list: D000900:Anti-Bacterial Agents
keywords: allergic rhinitis; antibiotics; epidemiology; farm living; infant; newborn