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University of California, San Francisco, researchers analyzed data from nearly 2,500 black and Hispanic children and found that those aged 8 to 17 with uncontrolled asthma were far more likely to have mothers who smoked during pregnancy.
This finding did not change when the researchers controlled for factors such as education, socioeconomic level and childhood exposure to tobacco smoke.
Asthma that is not controlled by regular medication results in more "asthma attacks," or acute flare-ups.
"If women smoked while pregnant, their children had about a 50 percent increase in uncontrolled asthma, even when we controlled for current tobacco exposure," study first author Sam Oh, a postdoctoral scholar in epidemiology at the UCSF Center for Tobacco Research and Education, said in a university news release. "Kids who are 17 years old still show the effects of something they were exposed to during the first nine months of life."
The researchers suggested two possible reasons for the increased risk of acute asthma in children whose mothers smoked during pregnancy. Either the infant's lungs are damaged during development in the womb, or the exposure to tobacco smoke causes a genetic change.
Oh and colleagues also found that the exact timing of tobacco exposure during pregnancy (such as whether it was in the first or third trimester) was less important than whether mothers smoked at all. However, children with asthma symptoms were more likely to have mothers who smoked during all nine months of pregnancy.
The study appears online May 31 and in an upcoming print issue of the Journal of Allergy and Clinical Immunology.
The researchers noted that women from ethnic minorities are more likely to smoke during pregnancy, and that asthma rates among blacks and Hispanics are higher than in the overall U.S. population.
-- Robert Preidt
Copyright © 2012 HealthDay. All rights reserved.
SOURCE: University of California, San Francisco, news release, May 31, 2012