title: Is large birth weight associated with asthma risk in early childhood?
abstract: OBJECTIVE
  To determine the association between large birth weight and the risk of developing asthma in early childhood.
  
  
  METHODS
  All single live births (n=687 194) born in Ontario between 1 April 1995 and 31 March 2001 were followed until their sixth birthday. Their birth weight was categorised as low (<2.5 kg), normal (2.5-4.5 kg), large (4.6-6.5 kg) or extremely large (>6.5 kg). Poisson regression analysis was used.
  
  
  RESULTS
  Compared with normal-birth-weight infants, large-birth-weight infants (2.3% of total) had a slightly lower risk of developing asthma by age 6 after adjusting for confounders (adjusted RR 0.90, 95% CI 0.86 to 0.93). There was a trend towards increased risk of asthma among extremely large-birth-weight infants (RR 1.21, 95% CI 0.67 to 2.19).
  
  
  CONCLUSIONS
  Contrary to previous reports, large birth weight was associated with a lower risk for asthma. Instead, a trend towards increased risk of asthma was observed among extremely large-birth-weight infants and interventions to reduce the incidence of extreme large birth weight may help reduce the risk of asthma.
authors.affiliation: Child Health Evaluative Sciences, The Hospital for Sick Children, 555 University Avenue, Toronto, Ontario M5G 1X8, Canada. teresa.to@sickkids.ca
authors.forename: Teresa
authors.initials: T
authors.lastname: To
authors.forename: Jun
authors.initials: J
authors.lastname: Guan
authors.forename: Chengning
authors.initials: C
authors.lastname: Wang
authors.forename: Dhenuka
authors.initials: D
authors.lastname: Radhakrishnan
authors.forename: Susan
authors.initials: S
authors.lastname: McLimont
authors.forename: Oxana
authors.initials: O
authors.lastname: Latycheva
authors.forename: Andrea S
authors.initials: AS
authors.lastname: Gershon
mesh_terms: D001249:Asthma / Q000453:epidemiology / Q000209:etiology* / Q000517:prevention & control; D001724:Birth Weight; D004630:Emergencies; D005260:Female; D005500:Follow-Up Studies; D006760:Hospitalization / Q000706:statistics & numerical data; D006801:Humans; D007230:Infant, Low Birth Weight; D007231:Infant, Newborn; D008297:Male; D009864:Ontario / Q000453:epidemiology; D018570:Risk Assessment / Q000379:methods