Effect of Breastfeeding on Asthma, Lung function, and Bronchial Hyperreactivity in ISAAC-Phase-Two

¹ Institute of Epidemiology, Ulm University, Germany
² Institute of Environmental Medicine, Karolinska Institutet Stockholm, Sweden
³ Capital Institute of paediatrics, Beijing, P. R. China
⁴ Guangzhou Institute of Respiratory Diseases, The First Affiliated Hospital of Guangzhou Medical College, Guangzhou, PR China; and Firestone Institute for Respiratory Health, St. Joseph's Healthcare, Hamilton; and Dept of Medicine, McMaster University, Hamilton, Ontario, Canada.
⁵ Norwegian Institute of Public Health, Division of Epidemiology, Tromso, Norway
⁶ Dept. of paediatric Allergy and Asthma, Hacettepe University, Ankara, Turkey
⁷ Dept of Public Health and Research, Sundsvall Hospital, Sweden
⁸ Paediatric Dept, Torrecárdenas Hospital, Almería, Spain
⁹ Paediatric Allergy and Pulmonology Unit, Doce de Octubre University Children's Hospital, Madrid, Spain

^* To whom correspondence should be addressed. E-mail: gabriele.nagel{at}uni-ulm.de.

	Abstract

We evaluated the association between breastfeeding and wheezing, lung function and atopy in the International Study of Asthma and Allergy in Childhood (ISAAC) Phase Two.

Cross-sectional studies were performed in 27 centres in 20 countries. Information on disease and exposure factors was collected by parental questionnaire. We used data from 54,000 randomly selected schoolchildren (eight-12 years, 31,759 with skin prick testing) and a stratified subsample (N=4,888) for testing correlation of breastfeeding with bronchial hyperreactivity and lung function. Random effect models for meta-analysis were applied to calculate combined odds ratios (OR).

Any breastfeeding was associated with less wheeze both in affluent (OR_adj, 0.87; 95% CI, 0.78–0.97) and non-affluent countries (OR_adj, 0.80; 95% CI, 0.68–0.94). Further analyses revealed that this was true only for non-atopic wheeze in non-affluent countries (OR_adj, 0.69; 95%-CI: 0.53–0.90). Breastfeeding was not associated with atopic wheeze and objective measures of allergy in both affluent and non-affluent countries. In contrast, breastfeeding was associated with higher predicted FEV₁ only in affluent countries (mean ratio, 1.11; 95% CI, 1.02–1.20).

Breastfeeding is associated with protection against non-atopic wheeze, which becomes particularly evident in non-affluent countries. Overall, breastfeeding was not related to any measure of allergy. These findings may explain some of the controversy regarding breastfeeding, since the direction of the association with breastfeeding depends on the predominating wheeze phenotype (e.g. atopic, non-atopic).