By itself, stress or socioeconomic status did not increase the risk of developing asthma, the researchers found.
However, when parental stress was combined with traffic pollution or exposure to smoking before birth, the risk of asthma increased more than it did for children exposed to pollution or smoke, but not stress.
Shankardass noted that exposure to traffic pollution and prenatal smoking as well as stress are more common in lower socioeconomic areas, which may help explain why asthma may disproportionately affect children of disadvantaged parents.
"For once, we may have a piece of the puzzle that would explain the social disparities in asthma," he said.
Dr. Clifford Bassett, medical director of Allergy and Asthma Care of New York, said it is not surprising that parental stress can have an impact on children and asthma.
"Stress does have an impact on the immune system. Clearly, the relationship between stress, tobacco and air pollution are all bad guys," Bassett said.
"There are many different variables -- behavioral, socioeconomic, environmental and physiologic -- that dictate whether a child will develop asthma," Bassett added. "There are a lot of biologic pathways that are involved in the relationship of asthma and stress and the immune system."
Bassett also thinks gauging household stress should be part of treating children with asthma.
For more information on asthma, visit the U.S. National Library of Medicine.
SOURCES: Ketan Shankardass, Ph.D., postdoctoral research fellow, Centre for Research on Inner City Health, The Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto; Clifford Bassett, M.D., fellow, American Academy of Allergy, Asthma and Immunology, and medical director, Allergy and Asthma Car
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