Children born during the fall months are at greater risk of developing asthma than babies born any other time of year, according to a new study.

The research, published in the American Journal of Respiratory and Critical Care Medicine, finds that children born four months prior to the winter virus peak are 30 percent more likely to develop childhood asthma.

Although the reason is unclear, scientists offer two possible explanations for the link between autumn births and asthma.

First, it is possible that there is a genetic susceptibility which is common to bronchiolitis and asthma development. And second, perhaps winter viral infections and other environmental exposure may cause asthma.

Dr. Tina Hartert of the center of Asthma Research at Vanderbilt University and principle researcher for the study says that predicting the peak of winter virus season is difficult because the season varies every year.

But, Dr. Hartert says avoiding infection for infants is even harder with 70 percent developing an infection by their first birthday.

An estimated 6.8 million children had asthma in 2006 and it is the leading serious chronic illness in the U.S., according to the American Lung Association.