Newborns whose first few months of life coincide with high pollen and mold seasons are at a higher risk of developing early symptoms of asthma. Many studies have found that the risk of childhood asthma varies by month of birth, but few have examined allergens in air as an explanatory factor. To examine whether being born during seasons with high fungal spore or pollen levels influenced the risk of wheezing, researchers from America studied 514 children from birth till one year of age. Early wheezing was determined from medical records and ambient allergen concentrations in air were measured throughout the study period and discrete seasons of high spore and pollen concentrations were defined. It was found that birth during these seasons, which typically runs from autumn to winter, increased the risk of early wheezing nearly threefold. Moreover, elevated levels of pollen, and basidiospores and ascospores, two common outdoor fungal particles, in the first three months of life also increased the risks of wheezing. High total pollen concentration exposure during the first three months of life was also linked to greater risk of early wheezing. The above findings shed light on why babies born in autumn and winter appear to have a higher risk of eventually developing asthma and allergies than children born in the summer.
Thorax
April 2009