Duration and exclusiveness of breastfeeding and risk of childhood atopic diseases.

Abstract

Breastfeeding may have immune modulatory effects that influence the development of childhood allergic sensitization and atopic diseases. We aimed to examine the associations of breastfeeding with childhood allergic sensitization, inhalant or food allergy and eczema, and whether any association was affected by disease-related modification of the exposure or modified by maternal history of allergy, eczema, or asthma. This study among 5828 children was performed in a population-based prospective cohort from fetal life onwards. We collected information on duration (<2months, 2-4months, 4-6months, and ≥6months) and exclusiveness (nonexclusive vs exclusive for 4months) of breastfeeding in infancy by postal questionnaires. At age 10years, inhalant allergic sensitization and food-allergic sensitization were measured by skin prick tests, and physician-diagnosed inhalant and food allergy by a postal questionnaire. Data on parental-reported eczema were available from birth until age 10years. We observed no association of breastfeeding with any allergic sensitization, physician-diagnosed allergy, or combination of these outcomes. Shorter breastfeeding duration was associated with an overall increased risk of eczema (P-value for trend <.05). Nonexclusively breastfed children had an overall increased risk of eczema (adjusted odds ratio [95% confidence interval]: 1.11 [1.01, 1.23]), compared with children exclusively breastfed for 4months. Risk period-specific sensitivity analyses, additional adjustment for ointment use for eczema at age 2months, and cross-lagged modeling showed no consistent results for disease-related modification of the exposure. Results were not modified by maternal history of allergy, eczema, or asthma (lowest P-value for interaction=.13). Shorter duration or nonexclusiveness of breastfeeding is associated with a weak overall increased risk of eczema but not allergic sensitization or physician-diagnosed allergy at age 10years.