A study examines hair cortisol (a biomarker of chronic stress) from birth to 7 years, describing its developmental trajectory
Researchers from the “Gestastress-Childstress” project (CTS-581 research group, CIMCYC, University of Granada) have published a study examining how hair cortisol levels evolve during early childhood and which factors may influence them.
To this end, a longitudinal follow-up of 212 mother–child dyads was conducted from birth to 7 years of age. Hair cortisol levels were assessed in newborns, at 6 months, and annually thereafter up to age 7. Hair samples were collected from the posterior vertex of the head, as close as possible to the scalp. The 3 cm segment closest to the scalp was analyzed, reflecting approximately the cortisol accumulated over the previous 3 months and thus providing a biological measure of chronic stress.
Until now, it has remained unclear how these levels evolve across childhood or which factors may influence them. Understanding the developmental trajectory of this biomarker, as well as its expected levels according to age or sex, is essential for its appropriate interpretation in research, whether as a predictor, mediator, or outcome of mental health problems, as currently explored in the scientific literature.
The results show a decrease in cortisol levels from birth to 3 years of age, followed by a period of stability between 4 and 7 years. The most pronounced decline occurs between birth and 6 months, after which the decrease becomes more gradual. This pattern may reflect the maturation of biological stress systems, as well as the fact that many stimuli are novel and potentially stressful during early life.
In addition, cortisol levels in childhood were higher than those typically observed in adults, which may be related to its role in organ development. Higher levels were also found in girls, but only at 3 years of age. Finally, the study provides descriptive percentiles for early ages (from newborns to 3 years).
These findings may help future research better understand the relationship between biological stress in childhood and the development of mental health problems, both in children and within their families.
Reference
Baos‐González, M. Á., De Echarri‐Lorente, J., García‐León, M. Á., González‐Pérez, R., & Peralta‐Ramírez, M. I. (2026). Hair Cortisol Concentrations in Children: A Longitudinal Analysis Across Childhood. Developmental Psychobiology, 68(3), e70154. https://doi.org/10.1002/dev.70154
Contact
Miguel Ángel Baos-González - @email