Skin prick tests
Skin prick tests (SPTs) were conducted at ages 3 and 7 years for 18 allergens using normal saline and histamine as a negative and positive control, respectively (15). The 18 allergens are specified in the online supplement. A positive SPT was defined by a mean wheal diameter of ≥ 3 mm and at least as large as that of the positive control. ImmunoCAP tests were conducted at ages 1, 3, and 7 years. The target allergen for the ImmunoCAP test according to the child’s age was: specific IgE to egg whites and milk for age 1; egg white, milk, and Der f for age 3; and egg white, milk, Der f , birch, and Alternaria for age 7. Children were considered sensitized if they exhibited positive results for SPT or if any specific IgE levels were ≥ 0.35kUA/L.