Early Day Care May Lower Asthma Risk
Day Care Attendance Before Age 3 Months May Cut Asthma Risk for Some Children
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
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
"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
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
Longer Follow-up Needed
Allergist David Tanner, MD, of the Atlanta Allergy & Asthma Clinic,
calls the findings interesting but preliminary.
"The unanswered question is, 'What happens to these kids five years
later?'" he says. "This study assumes that [lower IgE levels] correlate
with some degree of protection against developing allergies later on."
Tanner advises parents of high-risk children to avoid day care early on if
possible because of the known link between day care and an increased risk for
"In the long run day care may protect against asthma, but we can't
really say that yet," he says. "What we can say is that young children
with a family history of asthma or who have already experienced wheezing with a
viral infection will have more viral infections if they are in day