ROTTERDAM, Netherlands, Sept. 11 (UPI) -- Dutch researchers say their findings do not support the "hygiene hypothesis" that children who attend early day care do not have asthma later.

The study, published in American Journal of Respiratory and Critical Care Medicine, found any perceived protection against asthma and allergies due to greater exposure to illnesses disappeared by age 8.

Dr. Johan de Jongste of Erasmus University in Rotterdam, the Netherlands, and colleagues tracked more than 3,500 Dutch children in the Prevention and Incidence of Asthma and Mite Allergy Study and found children starting day care early -- before age 2 -- were twice as likely as those not going to day care to experience wheezing in the first year of life.

A slight trend for less wheezing among early day care attendees was noted by age 5, but by age 8, there was no protective or harmful effect. The effects of day care on wheezing did not differ between boys and girls, but were more marked in children with older siblings.

"Early day care merely seems to shift the burden of respiratory morbidity to an earlier age where it is more troublesome than at a later age," de Jongste, the chief investigator, said in a statement. "Early day care should not be promoted for reasons of preventing asthma and allergy."