Babies who are born in autumn, four months before the peak of winter virus season, have a higher risk of developing childhood asthma, a new study published in the American Journal of Respiratory and Critical Care Medicine has shown. A possible explanation may be the fact that the timing increases the chance of a viral respiratory problem in infancy which may determine an increased risk of childhood asthma.

Researchers at Vanderbilt University, in Nashville, analyzed the medical records of 95,000 children and their mothers from birth to early childhood to determine whether date of birth in relationship with the peak in winter respiratory viruses posed a higher risk for developing early childhood asthma. The children who participated in the study were born in Tennessee and enrolled in the state’s Medicaid program, TennCare.

According to the study, babies born in the fall had a 29 percent higher risk of asthma.

“Children in the Northern hemisphere born in the fall months have the highest rates of asthma, which suggests that winter viruses, like RSV, cause asthma,” said the first author of the study, Dr. Tina Hartert, director of the Center for Asthma Research and Environmental Health at Vanderbilt University School of Medicine, in Nashville, Tenn.

Experts agree that a family history of asthma combined with early life infections by respiratory viruses seem to increase the risk for asthma. Parents should not worry if they are going to have a baby born in the fall months, as doctors say birth timing is just one of the elements that might contribute to an increased risk of asthma.