CHICAGO (AP) - There may be a payoff to all the sniffling and coughing by children who attend day care: A study suggests they will probably get fewer colds in elementary school.

Children in large day-care centers - those with six or more children - appear to develop immunity to many of the viruses responsible for the common cold, according to the study.

The findings support a long-held theory among some pediatricians.

The study, published in February's Archives of Pediatrics and Adolescent Medicine, found that children in day care had almost twice as many colds at age 2 as those cared for at home. But from ages 6 to 11, children who had attended large day-care centers as toddlers had about one-third as many colds as those who stayed home.

The advantage disappeared by age 13, and both groups appeared to have the same degree of protection.

The study's lead author, Dr. Thomas M. Ball, associate professor of pediatrics at the University of Arizona College of Medicine, said the findings should help relieve the guilt and anxiety parents often feel when putting their children in day care.

"Personally, I've been telling people this for years because there is so much angst on the part of parents," Ball said. "I would like to reassure parents of preschoolers that, when their child has colds, they should know the child's immune system is learning from this experience, and that will come back to protect them later."

The researchers followed 991 children. In an accompanying editorial, Dr. Abraham B. Bergman of Harborview Medical Center and the University of Washington said the study proved "there is a silver lining to early viral illnesses."

"The benefit to colds in the toddler years is that kids miss less school later, when it counts," Bergman said.

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