We've previously discussed factors that influence the development of allergies and asthma in children. For instance, children born by c-sections and aren't exposed to as much bacteria during their birth are more likely to develop allergies. Those whose mothers take probiotics during pregnancy are less likely to develop allergies. In addition, children who are exposed to dogs are less likely to develop eczema.

Science Daily's Few Allergies in Unstressed Babies, Swedish Researchers Find covers a recent study from Karolinska Institutet in Sweden. The study sheds light on an additional factor that affects allergy development: cortisol levels in infants. Published in the December paper issue of the Journal of Allergy and Immunology, the study shows that infants with low levels of the hormone cortisol in their saliva develop fewer allergies than other infants.

As Dr. Fredrik Stenius of the Department of Clinical Research and Education at Stockholm South General Hospital says, ‘Psychosocial factors and the stress hormone cortisol are associated with allergic diseases. 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.’

Such information adds to the growing body of research that attempts to answer the question of why allergic disease is on the rise, and hopefully will contribute to new ways of looking at how to address the issue.