How, when and where a child is born may all play a role in lifetime asthma risk, new studies suggest.
Asthma occurs when airways in the lungs spasm and swell, restricting the supply of oxygen. The incidence of asthma in the United States has risen steadily for more than two decades, and now affects about 6 percent of children, up from less than 4 percent in 1980, according to the Centers for Disease Control and Prevention.
The reasons for the increase are not entirely clear. Genetics probably plays a role in risk for asthma, but an array of environmental factors — pollen, dust, animal dander, mold, cockroach feces, cigarettes, air pollution, viruses and cold air — have all been implicated in its development.
This month, The American Journal of Respiratory and Critical Care Medicine is reporting that children born in the fall have a 30 percent higher risk for asthma than those born in other seasons. The finding is based on a review of birth and medical records of more than 95,000 children in Tennessee.
A possible explanation is that autumn babies tend to be about 4 months old at the peak of cold and flu season. By that age, many babies are in day care, regularly exposed to the outside world.
And while their lungs are still developing, they have lost immunities conferred in the womb and have yet to develop their own strong immune systems. As a result, fall babies are at particular risk to contract a severe winter virus, which may in turn increase their risk for asthma. Read more…