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    Early Day Care May Lower Asthma Risk

    Day Care Attendance Before Age 3 Months May Cut Asthma Risk for Some Children
    WebMD Health News
    Reviewed by Louise Chang, MD

    Oct. 18, 2007 -- Attending day care from early infancy may help protect high-risk children from developing asthma, new research suggests.

    Regular day care attendance by 3 months of age was linked to lower levels of immunoglobulin E (IgE) antibodies in the University of Arizona study, but the association was seen only among children whose mothers had asthma or had positive skin tests for allergies.

    IgE antibodies trigger the inflammatory responses that cause allergies and related asthma.

    Researchers found that the IgE levels of children who started day care in early infancy remained low for at least the first three years of life.

    The findings add support to the 'hygiene hypothesis' suggesting that early exposure to germs from different environments helps protect against allergies and asthma caused by allergic responses, researcher Anne L. Wright, PhD, tells WebMD.

    "This study doesn't prove cause, but it adds to the evidence suggesting a protective effect by linking day care to this early predictor of asthma risk," she says.

    Early Day Care Exposure Is Key

    Asthma is the most common chronic disorder in childhood, affecting an estimated 6.2 million children in the U.S. under the age of 18, according to the American Lung Association.

    Allergies are important asthma triggers in children, but they are not the only ones. Respiratory infections, secondhand cigarette smoke exposure, exercise, and stress are also important triggers.

    In the study, the researchers examined the timing of day care exposure and the specific aspects of exposure that might influence a child's risk of developing allergic asthma.

    They found that entering day care before the age of 3 months was associated with decreased IgE levels three years later in high-risk children (those with mothers who had asthma or allergies), but entering day care later in infancy or childhood was not protective.

    The finding supports the idea of a "critical window of vulnerability" during which exposures influence the developing immune system, Wright says.

    Being outside the home seemed to be a more important predictor of lower IgE levels later in life than the number of other children a child was exposed to.

    This finding led the researchers to speculate that regular exposure to germs from two separate environments may play a greater role in immune response than early exposure to other children.

    The study is published in the latest issue of the Journal of Allergy and Clinical Immunology.

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