Rationale Breastfeeding protects from respiratory infections in early life but its relationship to recurrent cough and other respiratory outcomes in adult life is not well established.
Methods Infant feeding practices were assessed prospectively in the Tucson Children’s Respiratory Study, a non-selected birth cohort and categorised into formula from birth or introduced <1 month, formula introduced ≥1 to <4 months and exclusive breastfeeding for ≥4 months. Infant feeding was assessed as an ordinal variable representing an increasing dose of breastmilk across the three categories. Recurrent cough was defined at 22, 26 and 32 years as ≥2 episodes of cough without a cold lasting 1 week during the past year. Covariates included participant sex, race/ethnicity and smoking as well as parental smoking, education, age and asthma. Covariates were evaluated as potential confounders for the relation between infant feeding and adult outcomes.
Results Of the 786 participants, 19% breastfed <1 month, 50% breastfed ≥1 to <4 months and 31% breastfed ≥4 months. The prevalence of recurrent cough at 22, 26 and 32 years was 17%, 15% and 16%, respectively. Each ordinal increase in breastfeeding duration was associated with a decreased risk of recurrent cough in adult life: adjusted OR=0.71, (95% CI: 0.56 to 0.89), p=0.004. Additional adjustment for concurrent adult asthma, wheeze, smoking and lung volume did not change these results.
Conclusion Longer duration of breastfeeding reduces the risk of recurrent cough in adult life, regardless of smoking and other respiratory symptoms, suggesting long-term protective effects on respiratory health.
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Contributors Study concept and design: FDM, ALW, DAS and KDG; participant recruitment: ALW; acquisition of data: ALW, FDM and WJM; analysis of data: DAS, KDG, SG, WJM and FDM; data interpretation and drafting of the manuscript: KDG, DAS, SG, WJM, ALW and FDM. All authors critically read, commented on and approved the final version of the manuscript.
Funding This work was supported by US Department of Health and Human Services, National Institutes of Health, National Heart Blood and Lung Institute grant number 132523.
Competing interests None declared.
Patient consent Not required.
Ethics approval This research was approved by the institutional review board of the University of Arizona.
Provenance and peer review Not commissioned; externally peer reviewed.
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