The association between breastfeeding and respiratory health in infants born to women with asthma: a secondary analysis of two cohort studies

Abstract

Whether breastfeeding protects against wheeze/ bronchiolitis in infants born to women with asthma is unclear. We examined the association between breastfeeding and respiratory outcomes in the first year of life in infants born to women with asthma. Two prospective cohort studies of pregnant women with asthma (N=624) and their infants, conducted between 2007-2018 (Newcastle, Australia) were analysed. Mothers completed a validated questionnaire (breastfeeding duration and exclusivity, infant respiratory events and healthcare utilisation) at 6±1 months (T1) and 12±1 months (T2) post-partum. Chi-squared tests and logistic regression models were used for analysis. Data were complete for n=607 at T1, with repeat measures on 80% (n=483) at T2. Of 607 participants: 89% (n=540) initiated breastfeeding, 54% breastfed for >6 months and at T2, 31% were still breastfeeding. Breastfeeding for >6 months vs. ‘never’ was associated with a reduced risk of wheeze (aRR 0.50, 95%CI 0.28-0.90) and bronchiolitis (aRR 0.47, 95%CI 0.24-0.92) at T1. Current breastfeeding vs. not current breastfeeding at T2 was also associated with a reduced risk of ‘wheeze ever’ (aRR 0.60, 95%CI 0.39-0.94). Breastfeeding for >6 months vs. ‘never’ was associated with a lower proportion of infants presenting to the emergency department at T2 (14% vs 30%, p=0.02). Breastfeeding in the first 6 months of life was associated with a reduced risk of parent-reported wheeze and bronchiolitis, and less healthcare utilisation, in infants born to women with asthma. Large cohorts are needed to examine the impact of longer duration breastfeeding, and exclusivity, on respiratory health in offspring.