Children born in the fall may face higher risks for developing asthma or allergies, suggest researchers at Henry Ford Health System.
The study measured the level of a protein known as IgE, an immunoglobulin that participates in allergic reactions, in 487 mostly white Detroit-area children followed from birth to age 7.
Results were presented yesterday at an American Academy of Allergy, Asthma and Immunology annual meeting.
Children born in September, October and November had average IgE levels of 67 international units per milliliter of blood. Children born in June, July or August had average levels of 32 units, said Dr. Dennis Ownby, director of allergy research at Henry Ford.
"It's essentially a doubling," he said. "That makes it unlikely that it's just a statistical fluke."
The higher the IgE level, the higher the risk of having an allergic disease and especially asthma, he said.
The ongoing study has not yet analyzed whether the children with higher IgE levels do in fact have higher incidents of allergies and asthma.
Ownby was not sure why the season of birth would influence IgE levels. "It's interesting but hard to explain," he said.
The study was launched to look at environmental factors that may trigger or influence asthma.
"Asthma has become a fairly common disease of children. Part of the reason they develop it is their hereditary background. But heredity only explains perhaps half of the risk of developing asthma," Ownby said.
University of Michigan internal medicine Associate Prof. Dr. Galen Toews, an asthma specialist, described the differences in IgE levels between summer and fall babies as "significant."
But, he said, the more important finding would be if babies born in the fall have higher rates of allergies and asthma.
Henry Ford researchers also presented early results of a study comparing asthma rates between black youngsters and white children.
Looking at IgE in the seasonal allergy group, and in 36 black children from a Detroit suburb, it found that black children's average level was 76 international units per milliliter, Ownby said. For white children, the average level was 28.
The finding could suggest that black children diagnosed with asthma need more aggressive treatment, he said.
According to a Centers for Disease Control and Prevention study released last year, blacks ages 5 to 14 were four times more likely than whites that age to die from asthma in 1993, the most recent year for which figures are available.
Asthma, the most common long-term illness in childhood, affects 4.8 million children in the United States, the CDC said.
It is an inflammatory disease that narrows the air passages to the lungs and causes wheezing and difficulty in breathing. Asthma attacs ckan be triggered by infections, allergies or environmental factors such as dust or tobacco smoke.
The overall rate of death from asthma among all people from birth to age 24 increased 118 percent - from 1.7 deaths per million people to 3.7 deaths per million people - from 1980 to 1993, the CDC said.