Study leader Dr. Tina V. Hartert of Vanderbilt University in Nashville and colleagues analyzed the medical records of more than 95,000 children and their mothers in Tennessee to determine whether date of birth in relationship to the peak in winter respiratory viruses posed a higher risk for developing early childhood asthma.

The study, scheduled to be published in the December issue of the American Journal of Respiratory and Critical Care Medicine, found that while having clinically significant bronchiolitis at any age during infancy was associated with an increased risk of childhood asthma, the risk was greatest for autumn babies.

"Infant age at the winter virus peak following birth independently predicts asthma development, with the highest risk being for infants born approximately four months prior to the peak, which is represented by birth in the fall months in the Northern hemisphere," Hartert said in a statement. "Birth during this time conferred a nearly 30 percent increase in odds of developing asthma."