NEW STUDY: Allergies and children in the U.S.

A new study reveals children who come to the United States have lower odds of developing asthma and allergies, than children born in the U.S.

Researchers say more than 20% of children born outside of the country had some type of allergic disease. That's compared to between 34% and 35% of children born in the U.S.

The lead researcher says this suggests there are ''environmental'' factors in the U.S. that trigger allergic disease.