First author Sam S. Oh, a postdoctoral scholar in epidemiology at the University of California, San Francisco, Center for Tobacco Research and Education, and colleagues analyzed nearly 2,500 Latino and African-American children with asthma.
The researchers found children ages 8-17 with acute asthma symptoms were far more likely than others to have been born to mothers who smoked during pregnancy -- even when the team controlled for elements such as education, socioeconomic level and childhood exposure to tobacco smoke.
"If women smoked while pregnant, their children had about a 50 percent increase in uncontrolled asthma, even when we controlled for current tobacco exposure," Oh said in a statement. "Kids who are 17 years old still show the effects of something they were exposed to during the first nine months of life."
The findings were significant because a greater proportion of women from ethnic minorities smoke throughout their pregnancies.
The findings were published online ahead of the print edition of The Journal of Allergy and Clinical Immunology.