WEDNESDAY, Sept. 17 (HealthDay News) -- Children who attended a daycare center as infants are 35 percent less likely than their peers to have asthma symptoms by age 5, according to new research.

The British study, published in The Journal of Allergy and Clinical Immunology, found those enrolled between age 6 months and 12 months were most likely not to develop the symptoms, experiencing a 75 percent reduction in asthma risk.

The findings support the "hygiene hypothesis" that the less exposure to infections and germs children have early in life, the more likely they may later develop asthma and allergies, a phenomenon seen in the developed world. Exposing young children to the pathogens in a daycare environment, it is believed, may help boost immune defenses against allergic diseases.

The study looked at more than 900 children, from birth through age 5.

Asthma affects as many as 9 million children in the United States, making it the most common chronic disease among U.S. children, according to the American Academy of Allergy, Asthma & Immunology. The condition is responsible for an estimated 15 million missed school days each year.

More information

The National Heart, Lung, and Blood Institute has more about potential causes of asthma.