Lack of exercise tops the list of the biggest concerns about kids' health, according to a new survey of American adults. The plight of young couch potatoes outranked teen pregnancy and drug abuse as problems that adults are concerned about, according to the survey.

Not getting enough exercise was ranked a "big problem" by 39 percent of adults surveyed, followed closely by childhood obesity (38 percent) and smoking and tobacco use (34 percent), according to the findings from the University of Michigan C.S. Mott Children's Hospital National Poll on Children's Health.

In last year's survey, childhood obesity topped the list, while "not enough opportunities for physical activities" didn't even make the top 10. The jump in the adults' concern about exercise may be due recent public health messages focused at this topic, researchers said.

"Childhood obesity remains a top concern, and adults know it is certainly linked to lack of exercise," Matthew Davis, director of poll, said in a statement.