This prospective birth cohort from New Zealand included 1,000 infants. Information about wheezing and current asthma was collected at 2, 3, 4, 5, and 6 years.
Each month of exclusive breastfeeding was associated with reductions in current asthma from 2 to 6 years. Current asthma at 2, 3, and 4 years was also reduced by each month of any breastfeeding.
In atopic children, exclusive breastfeeding for ≥3 months reduced current asthma at ages 4, 5, and 6 by 62%, 55%, and 59%, respectively.
The authors concluded that breastfeeding, particularly exclusive breastfeeding, protects against current asthma up to 6 years. The degree of protection beyond 3 years was more pronounced in atopic children.
Allergic (atopic) march (click here to enlarge the image):
Breastfeeding Protects against Current Asthma up to 6 Years of Age. Silvers KM, Frampton CM, Wickens K, Pattemore PK, Ingham T, Fishwick D, Crane J, Town GI, Epton MJ; New Zealand Asthma and Allergy Cohort Study Group. J Pediatr. 2012 Jun;160(6):991-996.e1. Epub 2012 Jan 30.
Image source: Wikipedia, GNU Free Documentation License.