Few allergies in unstressed babies, Swedish researchers find

The study is published in the December paper issue of Journal of Allergy and Clinical Immunology.

The incidence of allergies in children has increased over the past few decades, especially in the West. 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.

"Psychosocial factors and the stress hormone cortisol are associated with allergic diseases," says Dr Fredrik Stenius of the Department of Clinical Research and Education at Stockholm South General Hospital. "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 team has previously described a link between a lower prevalence of allergies in school children and an anthroposophic lifestyle.

"And now we've found the same link in infants from families that follow anthroposophic lifestyles, and that they have relatively low levels of cortisol," adds Dr Stenius, who earned his PhD earlier in the year with a thesis on the subject.

The researchers believe that factors related to stress regulation also influence the development of infant allergies and will now monitor the infants from the neonate period and into childhood.