Clues about childhood asthma and allergies may be contained in umbilical cord blood, according to a recent study.
Researchers studied samples of umbilical cord blood taken from 1,300 babies, who were later assessed at ages 1, 2, 4 and 10 to determine if they had developed asthma and/or allergies. By age 4, 20% of the children had become sensitized to allergens. By age 10, that figure rose to 27%.
The study found that children born with high levels of immunoglobulin E (IgE) in their umbilical cord blood were approximately twice as likely to become sensitized to allergens IgE is an immune system response that indicates sensitization to allergens, such as grass pollens, house dust mites and pet dander.
Of all the children in the study, 10% were diagnosed with asthma by the time they were 1 to 2 years old. That rose to 15.2% by age 4, and was approximately 13% at age 10.
High levels of IgE in umbilical cord blood were not associated with the development of asthma up to age 4, but the children who had elevated levels were approximately 66% more likely to have been diagnosed with asthma by age 10. This suggests that there is a late-onset form of asthma, according to the researchers.
Children who did not develop any allergies were more than three times as likely to have asthma by age 10 if they had high IgE cord blood levels.
The findings suggest that high levels of IgE in a newborn's umbilical cord may be more important in the development of childhood asthma and allergies than exposure or lack of exposure to allergens after birth.
Fetal immune system programming, say the study authors, could have more influence on the development of childhood allergies than what happens after a child is born.
What Is Asthma?
Asthma is an allergic reaction to substances A commonly breathed in through the air, such as animal dander, pollen or dust.
When people who are allergic to a substance breathe it in, the immune system treats it as a harmful invader and produces a molecule called immunoglobulin E (IgE), an antibody to fight the substance. This, in turn, can cause airways to become inflamed and constricted, leading to coughing and wheezing as well as difficulty breathing.
Approximately 17 million Americans, or 6.4% of the population, has asthma, according to the National Institute of Allergy and Infectious Diseases.