A study published in the Journal of Asthma assessed the association between breastfeeding duration and the prevalence of wheeze and asthma in Japanese children aged 3 years. The prevalence rates of wheeze and asthma were 19.5% and 7.0%, respectively. Exclusive breastfeeding for ≥4 months was not significantly associated with wheeze or asthma, when compared with <4 months of exclusive breastfeeding. Compared with <10 months of breastfeeding regardless of exclusivity, 10 to <14 months, 14 to <19 months, and >19 months of breastfeeding duration regardless of exclusivity were independently inversely related to asthma. There was no association between breastfeeding duration regardless of exclusivity and wheeze. Therefore, an inverse association was evident between breastfeeding duration regardless of exclusivity and asthma.