A new Harvard Medical School study has shown that, despite a popular misconception, obesity may be a leading cause of asthma among children.

Doctors and parents commonly believe that children with asthma become overweight because they are forced to eschew exercise due to their medical condition.

But the study, led by Assistant Professor of Medicine Carlos A. Carmago Jr., makes claims that obesity may lead to asthma among children.

"People have noticed that asthmatics tend to be more overweight," Carmago said. "There has not been much discussion that obesity causes asthma."

Camargo said he began researching the subject in 1996. "We were looking at many risk factors for asthma and [obesity] was one that occurred to us."

Camargo, working primarily with three other researchers, said he "found a rather striking association."

Over the course of three years, Camargo and his team studied 17,000 people between nine and 14 years old. The subjects were all children of registered nurses.

The study, released last week, showed that the more overweight children are, the more likely they are to develop asthma.

However, pediatricians should not automatically conclude that overweight asthmatics can be cured simply by losing weight, Camargo said.