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Open Access Research article

Is body size at birth related to circadian salivary cortisol levels in adulthood? Results from a longitudinal cohort study

Per E Gustafsson1*, Urban Janlert2, Töres Theorell3 and Anne Hammarström1

Author Affiliations

1 Dept of Public Health and Clinical Medicine, Family Medicine, Umeå University, Umeå, Sweden

2 Dept of Public Health and Clinical Medicine, Epidemiology and Global Health, Umeå University, Umeå, Sweden

3 Stress Research Institute, Stockholm University, Stockholm, Sweden

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BMC Public Health 2010, 10:346  doi:10.1186/1471-2458-10-346

Published: 17 June 2010

Abstract

Background

The hypothesis of fetal origins of adult disease has during the last decades received interest as an explanation of chronic, e.g. cardiovascular, disease in adulthood stemming from fetal environmental conditions. Early programming and enduring dysregulations of the hypothalamic-pituitary-adrenal (HPA axis), with cortisol as its end product, has been proposed as a possible mechanism by which birth weight influence later health status. However, the fetal origin of the adult cortisol regulation has been insufficiently studied. The present study aims to examine if body size at birth is related to circadian cortisol levels at 43 years.

Methods

Participants were drawn from a prospective cohort study (n = 752, 74.5%). Salivary cortisol samples were collected at four times during one day at 43 years, and information on birth size was collected retrospectively from delivery records. Information on body mass during adolescence and adulthood and on health behavior, medication and medical conditions at 43 years was collected prospectively by questionnaire and examined as potential confounders. Participants born preterm or < 2500 g were excluded from the main analyses.

Results

Across the normal spectrum, size at birth (birth weight and ponderal index) was positively related to total (area under the curve, AUC) and bedtime cortisol levels in the total sample. Results were more consistent in men than in women. Descriptively, participants born preterm or < 2500 g also seemed to display elevated evening and total cortisol levels. No associations were found for birth length or for the cortisol awakening response (CAR).

Conclusions

These results are contradictory to previously reported negative associations between birth weight and adult cortisol levels, and thus tentatively question the assumption that only low birth weight predicts future physiological dysregulations.