Neonatal birch-pollen contact and subsequent allergy to birch pollen


Dr F. Björkstén, Hospital for Allergic Diseases, SF-00250 Helsinki 25, Finland.


It is shown by regression analysis that the risk of immediate hypersensitivity to birch pollen, as measured by a skin test, is positively correlated with the quantity of birch male flowers and the number of non-rainy days in the first birch flowering season (May) met in infancy. The risk is also dependent on the month of birth, with maximal risk associated with birth in Februarys–April. The results suggest that early pollen contacts, particularly during the first 6 months of life, increase the risk of pollen allergy for a period of 20 years. We estimate that elimination of early birch pollen contacts could have reduced the prevalence of immediate hypersensitivity to birch by 28% in our age group 0–19 years.