Lack of evidence for a protective effect of prolonged breastfeeding on childhood eczema: lessons from the International Study of Asthma and Allergies in Childhood (ISAAC) Phase Two

Authors


  • Funding sources
    The coordination and central laboratory analyses of the European centre were supported by the Fifth Framework Programme of the European Commission, Brussels, Belgium (QLK4-CT-1999-01288). Pharmacia Diagnostics (Uppsala, Sweden) made reagents available at nominal cost. C.F. holds a National Institute for Health Research Clinician Scientist Award.

  • Conflicts of interest
    None declared.

  • Members of the ISAAC Phase Two Study Group are listed in Appendix 1. The views expressed in this publication are those of the authors and are not necessarily those of the NHS, the National Institute for Health Research or the U.K. Department of Health.

Carsten Flohr.
E-mail: carsten.flohr@kcl.ac.uk

Abstract

Summary Background  Exclusive breastfeeding for at least 4 months is recommended by many governments and allergy organizations to prevent allergic disease.

Objectives  To investigate whether exclusive breastfeeding protects against childhood eczema.

Methods  Study subjects comprised 51 119 randomly selected 8- to 12-year-old schoolchildren in 21 countries. Information on eczema and breastfeeding was gathered by parental questionnaire. Children were also examined for flexural eczema and underwent skin prick testing. Odds ratios (ORs) were calculated for each study centre and then pooled across populations.

Results  There was a small increase in the risk of reported ‘eczema ever’ in association with ‘breastfeeding ever’ and breastfeeding < 6 months [pooled adjusted OR 1·11, 95% confidence interval (CI) 1·00–1·22 and OR 1·10, 95% CI 1·02–1·20, respectively]. There was no significant association between reported ‘eczema ever’ and breastfeeding > 6 months (pooled adjusted OR 1·09, 95% CI 0·94–1·26). Risk estimates were very similar for exclusive breastfeeding < 2 months, 2–4 months and > 4 months and for eczema symptoms in the past 12 months and eczema on skin examination. As for more severe eczema, breastfeeding per se conveyed a risk reduction on sleep disturbed eczema (pooled adjusted OR 0·71, 95% CI 0·53–0·96), but this effect was lost where children had been exclusively breastfed for > 4 months (pooled adjusted OR 1·02, 95% CI 0·67–1·54). Allergic sensitization and a history of maternal allergic disease did not modify any of these findings.

Conclusions  Although there was a protective effect of ever having been breastfed on more severe disease, we found no evidence that exclusive breastfeeding for 4 months or longer protects against eczema. Our results are consistent with findings from a recent systematic review of prospective studies. The U.K. breastfeeding guidelines with regard to eczema should be reviewed. Intervention studies are now required to explore how and when solids should be introduced alongside breastfeeding to aid protection against eczema and other allergic diseases.

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