title: Cesarean section and chronic immune disorders.
abstract: OBJECTIVE
  Immune diseases such as asthma, allergy, inflammatory bowel disease, and type 1 diabetes have shown a parallel increase in prevalence during recent decades in westernized countries. The rate of cesarean delivery has also increased in this period and has been associated with the development of some of these diseases.
  
  
  METHODS
  Mature children born by cesarean delivery were analyzed for risk of hospital contact for chronic immune diseases recorded in the Danish national registries in the 35-year period 1977-2012. Two million term children participated in the primary analysis. We studied childhood diseases with a suspected relation to a deviant immune-maturation and a debut at young age. The effect of cesarean delivery on childhood disease incidences were estimated by means of confounder-adjusted incidence rate ratios with 95% confidence intervals obtained in Poisson regression analyses.
  
  
  RESULTS
  Children delivered by cesarean delivery had significantly increased risk of asthma, systemic connective tissue disorders, juvenile arthritis, inflammatory bowel disease, immune deficiencies, and leukemia. No associations were found between cesarean delivery and type 1 diabetes, psoriasis, or celiac disease.
  
  
  CONCLUSIONS
  Cesarean delivery exemplifies a shared environmental risk factor in early life associating with several chronic immune diseases. Understanding commonalities in the underlying mechanisms behind chronic diseases may give novel insight into their origin and allow prevention.
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Faculty of Health and Medical Sciences, University of Copenhagen & Danish Pediatric Asthma Center, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark; and bisgaard@copsac.com.
authors.forename: Astrid
authors.initials: A
authors.lastname: Sevelsted
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Faculty of Health and Medical Sciences, University of Copenhagen & Danish Pediatric Asthma Center, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark; and Department of Pediatrics, Naestved Hospital, Naestved, Denmark.
authors.forename: Jakob
authors.initials: J
authors.lastname: Stokholm
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Faculty of Health and Medical Sciences, University of Copenhagen & Danish Pediatric Asthma Center, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark; and.
authors.forename: Klaus
authors.initials: K
authors.lastname: Bønnelykke
authors.affiliation: Copenhagen Prospective Studies on Asthma in Childhood, Faculty of Health and Medical Sciences, University of Copenhagen & Danish Pediatric Asthma Center, Gentofte Hospital, University of Copenhagen, Copenhagen, Denmark; and.
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D000293:Adolescent; D002585:Cesarean Section / Q000706:statistics & numerical data*; D002648:Child; D002675:Child, Preschool; D002908:Chronic Disease; D005260:Female; D006801:Humans; D007154:Immune System Diseases / Q000453:epidemiology*; D007223:Infant; D007231:Infant, Newborn; D008297:Male
keywords: asthma; cesarean section; inflammatory disease; origins; prenatal; programming