study shows that mice lacking PR-A and PR-B (progesterone receptors) have increased uterine inflammation. Again, the inflammatory/pro-inflammatory effects of hormones may be regulated through receptors. This may be the reason that different stages of life elicit a different response with the same hormone.
knowledge of progesterone and its metabolites are important in the use of hormones. As the authors concluded here: "natural steroids should not be disparaged...an update on endocrinological knowledge and experience is rather mandatory for gynecologists". There in lies the problem. The IOM has shown that the average physician practices at a level of 17 years behind the current scientific knowledge and the environment created by medical governing bodies discourages questions, so as to protect the system.