ABSTRACT
PURPOSE: Early sensitization to outdoor aeroallergens such as tree, grass and weed pollen in the early period of infancy is very important in the development of seasonal bronchial asthma or allergic rhinitis. There is a suggestion that pollen contact during the first 6 months of life increases the risk of pollen allergy for 20 years or later. The aim of our investigation was to identify the relationship between sensitization to outdoor aeroallergens and the month and season of birth in childhood respiratory allergic disorders. METHODS: One hundred three seasonal allergic rhinitis and bronchial asthmatic children were enrolled for this study, and skin prick tests done for each patient to detect the sensitized allergens. Ragweed, mugwort, alder, hazelnut, elm, willow, birch, beech, oak, plane tree, orchard and timothy grass were used for outdoor aeroallergens. The relative risk (RR) for development of hypersensitivity to outdoor aeroallergen in children born in certain months was calculated. RESULTS: We found that relative risk of immediate hypersensitivity to each outdoor aeroallergen was dependent on the season and month of birth. Tree pollen was the most common sensitizing allergen in children who were born in spring (RR=2.12, P< 0.001) and May (RR=1.83, P=0.042), grass pollen was most common in summer (RR=2.06, P=0.046) and June-born children (RR=3.69, P< 0.001) ; weed pollen was the in fall (ragweed RR=2.89; mugwort RR=2.23, P< 0.001) and September-born children. (ragweed RR=2.10, P=0.029; mugwort RR=1.98, P=0.026) CONCLUSION: Exposure in early infancy to outdoor aeroallergens is an important risk factor in the subsequent development of bronchial asthma and allergic rhinitis.