BREASTFEEDING for at least four months was linked to lower asthma and IgE sensitization into young adulthood.
Exclusive breastfeeding for at least four months was associated with lower odds of asthma and Immunoglobulin E (IgE) sensitization through age 24 in a longitudinal birth cohort, offering new evidence that early feeding patterns may shape allergic outcomes well beyond childhood.
Breastfeeding and Asthma Risk
The analysis included 3,919 participants from a Swedish birth cohort with breastfeeding data collected at age one year. Asthma outcomes were tracked by questionnaire through age 24, while IgE levels were measured at ages 4, 8, 16, and 24 years. Using longitudinal analyses, the investigators found that exclusive breastfeeding for at least four months was associated with a 25% reduction in the overall odds of prevalent asthma up to young adulthood.
The inverse association was strongest earlier in life. Age specific analyses showed a statistically significant association with lower asthma risk through age 12, but not beyond that point. When asthma patterns over time were examined more closely, exclusive breastfeeding was significantly associated with lower odds of persistent asthma and showed a borderline significant inverse association with early transient asthma. No association was observed for late onset asthma.
IgE Sensitization Also Reduced
The protective pattern extended beyond asthma alone. Exclusive breastfeeding for at least 4 months was also inversely associated with IgE sensitization overall, suggesting a broader relationship with allergic disease development.
Notably, the findings became even stronger after excluding 486 children who had early wheeze and or eczema during the breastfeeding period. That analysis reduced the possibility that early symptoms may have influenced feeding behavior, reinforcing the observed association between longer exclusive breastfeeding and lower asthma and sensitization risk.
What the Findings Suggest
Few studies have followed asthma and allergy related outcomes from infancy into adulthood with repeated immunologic assessment. This study adds longer term evidence suggesting that exclusive breastfeeding may be most relevant to asthma beginning in the first 12 years of life, rather than asthma that develops later.
The data do not suggest that breastfeeding prevents every asthma phenotype. Instead, they point to a more specific pattern, with benefit seen in early and persistent disease pathways and in IgE sensitization. For clinicians, that makes the findings especially relevant to conversations around infant feeding, early allergy risk, and long term respiratory health.
Reference
Kull I et al. Breast-feeding is inversely associated with asthma and IgE sensitization up to young adulthood. J Allergy Clin Immunol. 2026. doi:10.1016/j.jaci.2025.12.1011.
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