Of fibroids that develop in the uterus, Dr. John Lee * states that they are another perfect example of estrogen dominance secondary to anovulatory cycles and consequent progesterone deficiency. They generally occur in the 8-10 years before menopause. If sufficient natural progesterone is supplemented from day 12 to day 26 of the menstrual cycle, further growth of fibroids is usually prevented (and often the fibroids regress). 

Ovarian cysts are also a problem in many women. Dr. Peat says these are usually associated with a low thyroid condition, and that administration of thyroid hormone can get rid of them by lowering estrogen levels and making the ovaries produce more progesterone. 

Dr. Lee's approach, on the other hand, is to administer just the progesterone directly. He says that "natural progesterone, given from day 5 to day 26 of the menstrual month for two to three cycles, will almost routinely" cause disappearance of these cysts by suppressing normal FSH (follicle-stimulating hormone), LH (luteinizing hormone), and estrogen production and giving the ovary time to heal. Furthermore, studies have been reported in the Journal of the National Cancer Institute as far back as 1951 in which progesterone even produced evidence of regression of cervical tumors. 

It's reassuring to know that progesterone can protect us in so many ways; but we must all be cognizant to the fact that the long-range harmful effects of "estrogen dominance" in the body are not widely recognized.