title: Swimming pool attendance, asthma, allergies, and lung function in the Avon Longitudinal Study of Parents and Children cohort.
abstract: BACKGROUND
  Cross-sectional studies have reported inconsistent findings for the association between recreational swimming pool attendance and asthma and allergic diseases in childhood.
  
  
  OBJECTIVE
  To examine whether swimming in infancy and childhood was associated with asthma and allergic symptoms at age 7 and 10 years in a UK longitudinal population-based birth cohort, the Avon Longitudinal Study of Parents and Children.
  
  
  METHODS
  Data on swimming were collected by questionnaire at 6, 18, 38, 42, 57, 65, and 81 months. Data on rhinitis, wheezing, asthma, eczema, hay fever, asthma medication, and potential confounders were collected through questionnaires at 7 and 10 years. Spirometry and skin prick testing were performed at 7 to 8 years. Data for analysis were available for 5,738 children.
  
  
  RESULTS
  At age 7 years, more than 50% of the children swam once per week or more. Swimming frequency did not increase the risk of any evaluated symptom, either overall or in atopic children. Children with a high versus low cumulative swimming pool attendance from birth to 7 years had an odds ratio of 0.88 (95% confidence interval, 0.56-1.38) and 0.50 (0.28-0.87), respectively, for ever and current asthma at 7 years, and a 0.20 (0.02-0.39) standard deviation increase in the forced midexpiratory flow. Children with asthma with a high versus low cumulative swimming had an odds ratio for current asthma at 10 years of 0.34 (0.14-0.80).
  
  
  CONCLUSIONS
  This first prospective longitudinal study suggests that swimming did not increase the risk of asthma or allergic symptoms in British children. Swimming was associated with increased lung function and lower risk of asthma symptoms, especially among children with preexisting respiratory conditions.
authors.affiliation: Centre for Research in Environmental Epidemiology, Barcelona, Spain.
authors.forename: Laia
authors.initials: L
authors.lastname: Font-Ribera
authors.forename: Cristina M
authors.initials: CM
authors.lastname: Villanueva
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Nieuwenhuijsen
authors.forename: Jan-Paul
authors.initials: JP
authors.lastname: Zock
authors.forename: Manolis
authors.initials: M
authors.lastname: Kogevinas
authors.forename: John
authors.initials: J
authors.lastname: Henderson
mesh_terms: D001249:Asthma / Q000453:epidemiology*; D002648:Child; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004781:Environmental Exposure / Q000706:statistics & numerical data*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000453:epidemiology*; D008137:Longitudinal Studies; D008297:Male; D016017:Odds Ratio; D011446:Prospective Studies; D012129:Respiratory Function Tests; D012307:Risk Factors; D012882:Skin Tests; D013147:Spirometry; D011795:Surveys and Questionnaires; D013550:Swimming / Q000706:statistics & numerical data*; D013551:Swimming Pools; D006113:United Kingdom / Q000453:epidemiology