Background: 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.
Objective: 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.
Methods: 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.
Results: 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.
Conclusion: 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.
2011. Vol. 128, no 6, 1335-1339 p.