(Ivanhoe Newswire) -- Whether or not a child develops asthma may depend on his birthday.

Researchers at University of California at Berkeley found the risk increases for newborns whose first few months of life coincide with high pollen and mold seasons or the fall and winter months.

Numerous factors have been linked to asthma risk, including heredity and exposure to air pollution, animal dander and tobacco smoke. A 2008 study of birth and medical records found that babies born in the fall are at greater risk of later developing childhood asthma. That study suggested an influence from early exposure to respiratory viruses, which is more common during the peak of cold and flu season.

"In our study, we took a different tack to understand the link between month of birth and asthma by considering ambient concentrations of fungal spores and pollen, which follow distinct seasonal patterns," Kim Harley, associate director of health effects research at UC Berkeley's Center for Children's Environmental Health Research and lead author of the new study was quoted as saying.

"Until our paper, there were very little data about exposure to allergens in the air, which we know can trigger symptoms for those who already have asthma. This is the first study to look at the potential role of early life exposure to multiple outdoor fungal and pollen groups in the development of asthma,” said Harley.

SOURCE: Thorax online version, February 2009