Using a Biokinetic Model to Quantify and Optimize Cortisol Measurements for Acute and Chronic Environmental Stress Exposure in Maternal and Child Health

Abstract

Maternal stress during pregnancy may have significant health impacts on the developing fetus. To fully understand these impacts, it is necessary to quantify long-term and episodic stress during pregnancy. A wide range of approaches and protocols are available to assess maternal stress and stress biology in pregnancy, including stress-related biomarkers such as cortisol. Cortisol is released in pulses as part of the stress response, therefore instantaneous or short terms measurements in saliva, blood and urine can be unreliable measures of overall stress levels. In isolation of more dynamic measurements, cortisol in hair provides a relatively non-invasive, temporal and cumulative record of stress. Though there is a strong body of research relating psychological stress to elevated hair, blood, saliva and urine cortisol levels, there is little information regarding the relationship between the four compartments. Therefore, we used R (v. 2.14.2) to create a biokinetic model of cortisol levels using parameters obtained from the published literature that relates cortisol concentrations among these compartments. Additionally, we can show overall elevation or depression of cortisol and changes in pulsatile secretion. These values were used to create blood cortisol pulse profiles based on hair cortisol concentrations. This model will ultimately be adapted for pregnant women for potential use in national longitudinal cohort studies such as the National Children's Study to assess and quantify prenatal exposure to stress from maternal hair samples and stress questionnaires.