To examine the associations of breastfeeding duration and exclusiveness with the risks of asthma-related symptoms in preschool children, and to explore whether these associations are explained by atopic or infectious mechanisms.
This study was embedded in a population-based prospective cohort study among 5,368 children. Information on breastfeeding duration, exclusiveness and asthma-related symptoms, including wheezing, shortness of breath, dry cough and persistent phlegm, was obtained by questionnaires.
Compared to children who were breastfed for 6 months, those who were never breastfed had overall increased risks of wheezing, shortness of breath, dry cough and persistent phlegm during the first four years (Odds ratios 1.44 (95% Confidence Interval: 1.24, 1.66), 1.26 (1.07, 1.48), 1.25 (1.08, 1.44) and 1.57 (1.29, 1.91), respectively) Similar associations were observed for exclusive breastfeeding. The strongest associations per symptom per year were observed for wheezing at 1 and 2 years. Additionally adjusted analyses showed that the associations of breastfeeding with asthma-related symptoms were not explained by eczema but partly by lower respiratory tract infections.
Shorter duration and non-exclusivity of breastfeeding were associated with increased risks of asthma-related symptoms in preschool children. These associations seemed at least partly explained by infectious but not by atopic mechanisms.