Analysis of the relationship between pollinosis and date of birth in Switzerland.

Background: The first months of life may represent a vulnerable period in the development of atopic diseases. The objective of this study was to examine the relationship between the month of birth and the development of birch and grass pollen allergy in the Swiss population.

Methods: Data from the Swiss Study on Air Pollution and Lung Diseases in Adults(SAPALDIA) as well as the Swiss Study on Childhood Allergy and Respiratory Symptoms with Respect to Air Pollution and Climate (SCARPOL) were used. A logistic regression was calculated with grass and birch pollen sensitisation (positive skin prick test) or allergy (positive skin prick test and allergic symptoms) as outcome variables and the season of birth as predictor variable. The contribution of the season of birth on pollinosis was further adjusted for well-known risk factors and potential confounding variables.

Results: The logistic regression revealed a significant effect of the season of birth on birch pollen sensitisation and an effect of borderline significance on birch pollen allergy, i.e. subjects born in the pollen season (March to April) showed an increased risk of being sensitised/allergic to birch pollen. The results also indicated a tendency towards an increased risk for subjects born in the grass pollen season (May to June) to develop grass pollen allergy.

Conclusion: Our results support the hypothesis that the first few months of life constitute a sensitive period, during which inhalative exposure to certain allergens may predispose to the subsequent development of atopic respiratory disease.