Month of Birth and Risk of Immediate Hypersensitivity to Seasonal and Nonseasonal Antigens

The risk of immediate hypersensitivity to seasonal allergens has been reported to vary with month of birth. Serum samples from 631 children less than 18 years of age from the Detroit area were measured for allergen-specific immunoglobulin E (IgE) using an enzyme-linked immunosorbent assay. IgE to the seasonal allergens ragweed, timothy, and mite were measured, as well as to the relatively nonseasonal allergens cat, dog, and Alternaria. The number of positive tests for IgE ranged from 32% for mite to 58% for cat. The birth month distribution of children with positive tests was compared to the birth month distribution of all births in the Detroit metropolitan area. Some patterns were consistent with previous studies; however, there were no statistically significant differences with respect to the comparison population. Children with positive results to ragweed tended to be born more often during the August—October ragweed season. Sensitivity to mite was most common in July and August, a time period associated with high humidity in metropolitan Detroit. Children positive for cat IgE were more often born in February, July, and November; subjects positive to dog during June—September and children positive to Alternaria peaked in July. In contrast to other studies, children with positive IgE to timothy tended to be born less often during the May—June grass season.