Infant feeding practices and asthma in children aged 6 months to 5 years using a propensity score approach

We examined the association between exclusive breastfeeding, early introduction of feeding formula, early weaning, and asthma in children aged six months to five years in a sample of non-institutionalized US children using a propensity score approach. Our study used data from the National Survey of Children's Health (2012-2018) of 3,820 children with physician-diagnosed asthma aged 6 months to 5 years. Propensity score matching (PSM) was applied to control selection bias with age, sex, race, birth weight, Federal Poverty Level, parent's education, and parent smoking history used as covariates in PSM. The total number in the matched sample was 6,904 (3,452 non-asthmatics; 3,452 asthmatics). Matched and unmatched samples were analysed using the χ test and multiple logistic regression. Exclusive breastfeeding was protective against asthma in the pre-matching (AOR 0.72; 95% CI: 0.54-0.97; p = 0.03) and post-matching (AOR 0.66; 95% CI: 0.55-0.81; p < 0.001) samples. Formula feeding before 6 months was associated with asthma in unmatched (AOR 1.38; 95% CI: 1.15-1.66; p < 0.001) and matched (AOR 1.31; 95% CI: 1.16-1.47; p < 0.001) sample. Early weaning before 6 months was associated with asthma in unmatched (AOR 1.62; 95% CI: 1.35-1.54; p < 0.001) and matched sample (AOR 1.37; 95% CI: 1.23-1.54; p < 0.001). Public health systems should continue to recommend the implementation of the World Health Organization exclusive breastfeeding guideline in developed countries. Asthma interventions in children under two years should continue to emphasize exclusive breastfeeding to reduce the incidence of infant asthma.