PURPOSE OF THE STUDY.
To examine the association of breastfeeding and wheezing in the first year of life in a pregnancy cohort, with attention to maternal asthma and infant sex.
The study included 2773 infants born to women enrolled in the Canadian Healthy Infant Longitudinal Development (CHILD) Study, a population-based birth cohort, from 2009 to 2012.
Caregivers reported on infant wheezing and infant feeding via questionnaire at 3, 6, and 12 months of life. Breastfeeding was classified as exclusive, partial, or none. Poisson regression was used to examine the relationship between breastfeeding and wheezing rates, and logistic regression was used to investigate recurrent wheezing. Models were adjusted for maternal asthma, smoking, and education. Effect modification by maternal asthma and infant sex were also examined through stratification.
Twenty-one percent of women in the study had asthma, and 21% of infants wheezed. In mothers with asthma, breastfeeding was inversely associated with infant wheezing. Compared with no breastfeeding at 6 months, wheezing was reduced by 62% with exclusive breastfeeding. Wheezing was reduced by 37% with partial breastfeeding supplemented with foods. Breastfeeding was not significantly protective when supplemented with formula. There was a significant protective, dose-dependent association between breastfeeding and wheezing; the rate of wheezing was 0.63 episodes per person year among those breastfed <6 months, 0.5 in those breastfed for 6 to 12 months, and 0.31 in those who breastfed for 12 months or more. These findings were not significant in the absence of maternal asthma.
In infants born to mothers with asthma, breastfeeding was shown to be protective against wheezing in a dose-dependent manner. This association was somewhat stronger in male infants and independent of other established risk factors for infant wheezing. This association was weakened by supplementation with formula before 6 months of age.
The authors of this study add to the evidence that breastfeeding confers protection against wheezing in infants. The authors improved on limitations of previous studies by using a longitudinal study design with prenatal recruitment. In addition, in this study, the authors differentiated between exclusive and partial breastfeeding. The study was limited by parent-reported wheezing and only 1 year of follow-up in infants studied. Follow-up is underway in the Canadian Healthy Infant Longitudinal Development cohort and will glean important outcomes as we further our understanding of potential long-term benefits on reducing the prevalence of asthma.
- Copyright © 2017 by the American Academy of Pediatrics