Salivary cortisol levels and allergy in children: the ALADDIN birth cohort.

Abstract

Pre- and postnatal stress have been related to allergy in children, but evidence from prospective studies is limited. Several environmental factors can influence the salivary cortisol level, which is used as a measure of activity of the hypothalamic-pituitary-adrenal axis. The aim of this study was to assess the association between salivary cortisol levels at 6 months of age and allergic manifestations during the first 2 years of life. Salivary samples for the analysis of cortisol level were collected at 6 months of age on 3 occasions during 1 day from 203 children. Blood samples were collected at 6, 12, and 24 months of age for analyses of specific IgE. Information on allergy-related symptoms was obtained by repeated examinations of the children. Generalized estimating equation statistics were used to calculate the overall risk for outcome measures. The adjusted odds ratio for the relationship between morning cortisol level and IgE sensitization was 1.60 (95% CI, 1.22-2.10, P = .001) and for eczema it was 1.28 (95% CI, 1.03-1.59, P = .026). The odds ratio for afternoon cortisol level in relation to sensitization and eczema was 1.56 (95% CI, 1.26-1.94, P < .001) and 1.33 (95% CI, 1.12-1.58, P = .001), respectively, and for evening cortisol level it was 1.49 (95% CI, 1.22-1.83, P < .001) and 1.37 (95% CI, 1.18-1.59, P < .001). Salivary cortisol level in the evening was associated with food allergy. The association between salivary cortisol levels in infancy and allergic sensitization and allergic symptoms suggests a role of an altered hypothalamic-pituitary-adrenal axis in the etiological process of allergies.