Day care, older siblings help protect children against asthma.


University of Arizona researchers investigating the rapid increase in the number of cases of asthma followed more than 1,000 children from birth until they were 13 years old. They found that infants who had the most exposure to older children because they went to day care before the age of six months or had older siblings were more likely to have frequent wheezing during the years before they started school. But those same children were less likely to develop asthma between the ages of 6 and 13. They were also less likely to have compounds in the blood that show high allergic tendencies. The researchers pointed out that the number of U.S. families with more than two children has declined dramatically since 1970 and that although a majority of preschoolers go to day care, only 7 percent of infants under the age of 1 year do.

WHAT'S NEW Recent studies have suggested that the rise in asthma may be related to higher standards of personal hygiene, more day care and better infection control, all of which keep infants from developing what were once common childhood ailments. But this is the first study to factor in the effect of older siblings.

CAVEATS Reports were based on parents' recollections of wheezing. The researchers point out that the actual mechanism for development of asthma is still unknown.

BOTTOM LINE Although parents are often hesitant to expose children under the age of six months to other children by placing them in day care, youngsters may get some protection against asthma there.

FIND THIS STUDY Aug. 24 issue of the New England Journal of Medicine; abstract online at

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