title: Early life exposures: impact on asthma and allergic disease.
abstract: OBJECTIVE
  To identify and discuss recent studies relating prenatal and early-life environmental exposures to the development of asthma and allergic disease.
  
  
  RESULTS
  New studies show that prenatal and early-life stress can alter infant immune profiles, increasing risk for asthma and allergy. Mounting evidence implicates indoor and outdoor air pollution in the origins of allergic disease, while Vitamin D intake and a Mediterranean diet may be protective. The role of early-life fever and infection remain controversial, with recent studies yielding conflicting results and new evidence indicating that previous studies may have been confounded. New studies are increasingly focused on environmental 'imprinting' of the infant gut microbiota, which is a critical determinant of immune system development. Early exposures impacting the intestinal microbiota include mode of delivery, infant diet, and use of antibiotics - factors that are also associated with childhood asthma and allergic disease.
  
  
  CONCLUSIONS
  This overview highlights environmental exposures during the in-utero and ex-utero time periods that are potential stimuli for the early programming of asthma and allergy. Special consideration is given for the potential role of intestinal microbiota. Future studies in this field promise to inform health policy and intervention strategies for the prevention of asthma and allergic disease.
authors.affiliation: Department of Pediatrics, Faculty of Medicine and Dentistry, University of Alberta, Edmonton, Alberta, Canada. kozyrsky@ualberta.ca
authors.forename: Anita L
authors.initials: AL
authors.lastname: Kozyrskyj
authors.forename: Salma
authors.initials: S
authors.lastname: Bahreinian
authors.forename: Meghan B
authors.initials: MB
authors.lastname: Azad
mesh_terms: D017668:Age of Onset; D000397:Air Pollution / Q000009:adverse effects; D001249:Asthma / Q000178:diet therapy / Q000453:epidemiology* / Q000517:prevention & control; D015986:Confounding Factors, Epidemiologic; D036861:Delivery, Obstetric; D038441:Diet, Mediterranean; D005260:Female; D006801:Humans; D006967:Hypersensitivity / Q000178:diet therapy / Q000453:epidemiology* / Q000517:prevention & control; D007413:Intestinal Mucosa / Q000276:immunology* / Q000382:microbiology; D054892:Metagenome / Q000276:immunology*; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects / Q000178:diet therapy / Q000453:epidemiology* / Q000517:prevention & control; D012307:Risk Factors; D014807:Vitamin D / Q000627:therapeutic use
chemical_list: D014807:Vitamin D