title: Mode of delivery is not associated with asthma or atopy in childhood.
abstract: BACKGROUND
  Caesarean-section delivery has been associated with the subsequent development of atopy and wheezing in childhood.
  
  
  OBJECTIVE
  To examine the association between mode of delivery (vaginal vs. caesarean section) and development of atopy, asthma and wheezing disorders in a population-based cohort of children.
  
  
  METHODS
  The Avon Longitudinal Study of Parents and Children is a longitudinal birth cohort of children born 1 April 1991 to 31 December 1992. Mode of delivery was categorized as vaginal (including forceps and ventouse extractions) or caesarean section (elective and emergency). Primary outcomes were parental report of asthma or wheezing between 69 and 81 months of age, physician-diagnosed asthma (PDA) at 91 months of age and atopy at 7 years by skin prick testing. Possible confounding factors were considered in a multivariable logistic regression model.
  
  
  RESULTS
  Total livebirths were 14,062, from which were selected 12 367 born to mothers resident in a defined area and delivered in one of two major obstetric hospitals. Of these infants, 10,980 (88.8%) were delivered vaginally and 1387 (11.2%) by caesarean section. Outcome data were available for 7495 (61%) subjects (asthma 69-81 months); 7389 (60%) (wheeze 69-81 months); 7196 (58%) (PDA 91 months) and 5916 (48%) (atopy 7 years). Adjusted odds ratios [95%confidence interval] for caesarean section compared with vaginal delivery were not statistically significant for any outcome we considered: asthma 69-81 months 1.16 [0.9, 1.5]; wheeze 69-81 months 0.95 [0.7, 1.3]; PDA 1.14 [0.9, 1.4]; atopy 1.04 [0.8, 1.3].
  
  
  CONCLUSIONS
  Delivery by caesarean section was not associated with the subsequent development of asthma, wheezing or atopy in later childhood in this population.
authors.affiliation: Bristol Royal Hospital for Children, Bristol, UK. dramaitra@yahoo.co.uk
authors.forename: A
authors.initials: A
authors.lastname: Maitra
authors.forename: A
authors.initials: A
authors.lastname: Sherriff
authors.forename: D
authors.initials: D
authors.lastname: Strachan
authors.forename: J
authors.initials: J
authors.lastname: Henderson
mesh_terms: D000328:Adult; D001249:Asthma / Q000453:epidemiology / Q000209:etiology*; D001724:Birth Weight; D002585:Cesarean Section / Q000009:adverse effects; D002648:Child; D036861:Delivery, Obstetric / Q000009:adverse effects*; D004739:England / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D011247:Pregnancy; D015995:Prevalence; D011379:Prognosis; D011446:Prospective Studies; D012130:Respiratory Hypersensitivity / Q000453:epidemiology / Q000209:etiology*; D012135:Respiratory Sounds / Q000209:etiology; D006255:Rhinitis, Allergic, Seasonal / Q000276:immunology; D012307:Risk Factors; D012882:Skin Tests