title: Epidemiological aspects of and risk factors for wheezing in the first year of life.
abstract: OBJECTIVE
  To determine, in a sample of infants, the prevalence of and risk factors for occasional wheezing (OW) and recurrent wheezing-wheezy baby syndrome (WBS).
  
  
  METHODS
  Parents of infants (12-15 months of age) completed the International Study of Wheezing in Infants questionnaire.
  
  
  RESULTS
  We included 1,269 infants residing in the city of Blumenau, Brazil. Of those, 715 (56.34%) had a history of wheezing, which was more common among boys. The prevalences of OW and WBS were 27.03% (n = 343) and 29.31% (n = 372), respectively. On average, the first wheezing episode occurred at 5.55 ± 2.87 months of age. Among the 715 infants with a history of wheezing, the first episode occurred within the first six months of life in 479 (66.99%), and 372 (52.03%) had had three or more episodes. Factors associated with wheezing in general were pneumonia; oral corticosteroid use; a cold; attending daycare; having a parent with asthma or allergies; mother working outside the home; male gender; no breastfeeding; and mold. Factors associated with WBS were a cold; physician-diagnosed asthma; ER visits; corticosteroid use; pneumonia; bronchitis; dyspnea; attending daycare; bronchodilator use; having a parent with asthma; no breastfeeding; mother working outside the home; and a dog in the household.
  
  
  CONCLUSIONS
  The prevalence of wheezing in the studied population was high (56.34%). The etiology was multifactorial, and the risk factors were intrinsic and extrinsic (respiratory tract infections, allergies, attending daycare, and early wheezing). The high prevalence and the intrinsic risk factors indicate the need and the opportunity for epidemiological and genetic studies in this population. In addition, mothers should be encouraged to prolong breastfeeding and to keep infants under six months of age out of daycare.
authors.affiliation: Fundação Universidade Regional de Blumenau, Department of Medicine, Blumenau, Brazil. Department of Medicine, Fundação Universidade Regional de Blumenau, Blumenau, Brazil.
authors.forename: Hamilton Rosendo
authors.initials: HR
authors.lastname: Fogaça
authors.affiliation: State University at Campinas, School of Medical Sciences, Departments of Medical Genetics and Pediatrics, Campinas, Brazil. Departments of Medical Genetics and Pediatrics, State University at Campinas School of Medical Sciences, Campinas, Brazil.
authors.forename: Fernando Augusto de Lima
authors.initials: FA
authors.lastname: Marson
authors.affiliation: State University at Campinas, School of Medical Sciences, Department of Pediatrics, Campinas, Brazil. Department of Pediatrics, State University at Campinas School of Medical Sciences, Campinas, Brazil.
authors.forename: Adyléia Aparecida Dalbo Contrera
authors.initials: AA
authors.lastname: Toro
authors.affiliation: State University at Campinas, School of Medical Sciences, Department of Pediatrics, São Paulo, Brazil. Allergy, Clinical Immunology, and Rheumatology Section of the Department of Pediatrics, Federal University of São Paulo Paulista School of Medicine, São Paulo, Brazil.
authors.forename: Dirceu
authors.initials: D
authors.lastname: Solé
authors.affiliation: State University at Campinas, School of Medical Sciences, Center for Pediatric Research, Campinas, Brazil. Department of Pediatrics, Center for Pediatric Research, Pulmonary Physiology Laboratory, State University at Campinas School of Medical Sciences, Campinas, Brazil.
authors.forename: José Dirceu
authors.initials: JD
authors.lastname: Ribeiro
mesh_terms: D001249:Asthma / Q000150:complications; D001938:Brazil / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D012135:Respiratory Sounds / Q000209:etiology*; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D012737:Sex Factors; D011795:Surveys and Questionnaires
keywords: Asthma; Prevalence; Risk factors