title: Breastfeeding and asthma and allergies: a systematic review and meta-analysis.
abstract: OBJECTIVE
  To systematically review the association between breastfeeding and childhood allergic disease.
  
  
  METHODS
  Predetermined inclusion/exclusion criteria identified 89 articles from PubMed, CINAHL and EMBASE databases. Meta-analyses performed for categories of breastfeeding and allergic outcomes. Meta-regression explored heterogeneity.
  
  
  RESULTS
  More vs. less breastfeeding (duration) was associated with reduced risk of asthma for children (5-18 years), particularly in medium-/low-income countries and with reduced risk of allergic rhinitis ≤5 years, but this estimate had high heterogeneity and low quality. Exclusive breastfeeding for 3-4 months was associated with reduced risk of eczema ≤2 years (estimate principally from cross-sectional studies of low methodological quality). No association found between breastfeeding and food allergy (estimate had high heterogeneity and low quality). Meta-regression found differences between study outcomes may be attributable to length of breastfeeding recall, study design, country income and date of study inception. Some of the protective effect of breastfeeding for asthma may be related to recall bias in studies of lesser methodological quality.
  
  
  CONCLUSIONS
  There is some evidence that breastfeeding is protective for asthma (5-18 years). There is weaker evidence for a protective effect for eczema ≤2 years and allergic rhinitis ≤5 years of age, with greater protection for asthma and eczema in low-income countries.
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.|Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria, Australia.
authors.forename: C J
authors.initials: CJ
authors.lastname: Lodge
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.|NHMRC Centre of Research Excellence for Chronic Respiratory Disease, School of Medicine, University of Tasmania, Hobart, Tasmania, Australia.
authors.forename: D J
authors.initials: DJ
authors.lastname: Tan
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.
authors.forename: M X Z
authors.initials: MX
authors.lastname: Lau
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.
authors.forename: X
authors.initials: X
authors.lastname: Dai
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.
authors.forename: R
authors.initials: R
authors.lastname: Tham
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.|Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria, Australia.
authors.forename: A J
authors.initials: AJ
authors.lastname: Lowe
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.
authors.forename: G
authors.initials: G
authors.lastname: Bowatte
authors.affiliation: Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria, Australia.|Institute of Inflammation and Repair, University of Manchester, UK.
authors.forename: K J
authors.initials: KJ
authors.lastname: Allen
authors.affiliation: Allergy and Lung Health Unit, Centre for Epidemiology and Biostatistics, Melbourne School of Population and Global Health, The University of Melbourne, Carlton, Victoria, Australia.|Murdoch Childrens Research Institute and University of Melbourne Department of Paediatrics, Royal Children's Hospital, Parkville, Victoria, Australia.
authors.forename: S C
authors.initials: SC
authors.lastname: Dharmage
mesh_terms: D000293:Adolescent; D001249:Asthma / Q000453:epidemiology* / Q000517:prevention & control; D001942:Breast Feeding; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D015331:Cohort Studies; D003430:Cross-Sectional Studies; D004485:Eczema / Q000453:epidemiology*; D005260:Female; D005512:Food Hypersensitivity / Q000453:epidemiology*; D006801:Humans; D007223:Infant; D008297:Male; D065631:Rhinitis, Allergic / Q000453:epidemiology*; D013997:Time Factors
keywords: Allergic disease; asthma; meta-analysis; systematic review