The researchers adjusted the data to account for confounding factors, such as maternal education, mode of delivery, maternal smoking during pregnancy, duration of breast-feeding, birth weight and the child's current weight, according to Smit.
Although they found no association between maternal weight in children born to parents without asthma, children born to parents with asthma who also had an overweight mother had a 65 percent increased risk of developing asthma.
Though the study was not designed to determine why being overweight might affect a child's risk for asthma, Smit theorized that inflammation could be the connection between the conditions. That's because obesity can encourage inflammation, and inflammation is at the root of asthma.
Dr. Jennifer Appleyard, chief of allergy and immunology at St. John Hospital and Medical Center in Detroit, said that "we don't know exactly what causes or contributes to asthma, but it does look like there are some things that occur in utero that could affect the child later."
But, she said, it may not be the fact that mothers are overweight. It could be something that they're eating that's affecting their children. It's just not clear from this study, she said, adding that that more research needs to be done.
The U.S. National Heart, Lung, and Blood Institute has more on the causes of asthma.
SOURCES: H.A. Smit, Ph.D., head, Department of Prevention and Health Services Research, National Institute of Public Health and Environment, Bilthoven, the Netherlands; Jennifer Appleyard, M.D., chief, aller
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