It is surprising how little the medical community knows about progesterone, especially the consequences of a progesterone deficiency. In many cases, these consequences can be prevented with the use of natural progesterone replacement. It is fairly easy to diagnose women with low progesterone levels because these women are the ones who have PMS, severe menstrual cramps, headaches with their periods, and breast tenderness. They will be estrogen-dominant and very often will wind up with complications such as fibroids in the uterus and fibrocystic disease of the breast.