Stress-free babies develop fewer allergies: Study

Infants with low concentrations of cortisol, a stress-related hormone, in their saliva develop fewer allergies.

The incidence of allergies in children has increased over the past few decades. In Sweden, 30 to 40 percent of children have some kind of allergy.

A combination of environmental and lifestyle factors during pregnancy and early infancy are thought to be responsible for the sharp rise in allergic diseases, suggests a study from Karolinska Institutet in Sweden.

Hopefully this new knowledge will be useful in future allergy prevention, the Journal of Allergy and Clinical Immunology reports.

"Psycho-social factors and the stress hormone cortisol are associated with allergic diseases," says Fredrik Stenius of South General Hospital, Stockholm, according to a Karolinska Institutet statement.

"Our study found that children with low salivary cortisol levels as infants have a lower prevalence of allergies during the first two years of life, compared to other children."

The researchers believe that factors related to stress regulation also influence the development of infant allergies.