Relationship between salivary cortisol and progesterone levels in humans.

In four studies, each with multiple hormone assessments before and after positive emotion-arousing laboratory manipulations, salivary progesterone positively correlated with salivary cortisol in men and women taking hormonal contraceptives but not in freely cycling women. This is consistent with the idea that progesterone in men is largely adrenal in origin, whereas in women its sources are both ovarian and adrenal. In addition, bi-partial correlations revealed that change in cortisol was positively related to change in progesterone levels; this effect was stronger in men than in women. These findings suggest that progesterone is released from the adrenal along with cortisol in humans, due to general adrenal activation and/or possibly as an additional negative feedback mechanism to down-regulate the stress response.