Investigating the psychobiological stress response and the conversion of cortisol to cortisone in human pregnancy

Stress during human pregnancy is associated with various adverse consequences for the physiological and psychological wellbeing of mother and child. A main focus for the research field of stress during pregnancy is to identify the underlying biological mechanism by which the maternal psychological stress is transferred to the developing foetus. Glucocorticoids, such as cortisol seem to play a pivotal role, since an overexposure of maternal cortisol, for example due to psychological stress is capable of crossing the placental barrier and thereby reaching the foetus. Heightened cortisol levels in the prenatal period have been associated with preterm birth and low birth weight. In animal studies, the placental enzyme 11β-hydroxysteroid dehydrogenase type 2 (11β-HSD2) which converts active cortisol into its inactive metabolite cortisone, protects the developing foetus against an overexposure to maternal cortisol concentrations. This enzyme is also present in the adult salivary glands, where it exerts the same conversion of cortisol to cortisone. The aim of the present thesis was to examine the psychological and physiological stress reactivity of pregnant women confronted with a standardized stressor and to concurrently investigate the conversion of cortisol to cortisone in the saliva and amniotic fluid of pregnant women.