Asthma risk for autumn babies

By Jane Collingwood

Asthma rates are significantly higher for babies born in the autumn, according to new research.

A team from Vanderbilt University, Tennessee, USA, found that children born four months before peak cold and flu season have a higher risk of childhood asthma than other children.

The researchers investigated the medical records of over 95,000 children to see if their birth date, in relation to the winter peak in colds and flu, was linked to their asthma risk. This is indeed what they found – being born in the autumn was linked with a 29 per cent rise in asthma risk.

"Infant age at the winter virus peak independently predicts asthma development," said researcher Dr Tina Hartert, "The highest risk is for infants born approximately four months prior to the peak, represented by the autumn months in the Northern hemisphere."

Details of the research appear in the American Journal of Respiratory and Critical Care Medicine.

The experts believe that exposure to a winter virus may cause asthma. But avoiding winter viruses would be difficult, says Dr Hartert, because 70 per cent of infants catch an infection in their first year.

There are a number of ways to reduce the associated risks, she explains, such as timing the birth for spring months, or vaccination.

However, these ideas need to be studied further. "The next critical step is support for studies designed to determine whether prevention of the ubiquitous infections during infancy prevents childhood asthma," she says.

Wu, P. et al. Evidence of a Causal Role of Winter Virus Infection during Infancy in Early Childhood Asthma. The American Journal of Respiratory and Critical Care Medicine, Vol. 178, December 2008, pp. 1123-29.