Progesterone can be thought of as a hormonal balancer, particularly when it comes to the estrogens. Progesterone is a steroid hormone made by the corpus luteum of the ovary at ovulation, and in smaller amounts by the adrenal glands. It is the precursor, or substance from which most of the other steroid hormones are derived, including cortisol, androstenedione, the estrogens and testosterone. Progesterone has a remarkable repertoire of important jobs from normalizing blood sugar levels and facilitating thyroid hormone action to regulating menstrual cycles and maintaining a healthy pregnancy. The survival of the embryo in the womb absolutely depends on this vital hormone. Progesterone also has natural calming and diuretic properties, and it enhances the positive effects of estrogen, while preventing the problems associated with estrogen dominance. Unopposed estrogen can build to unsafe tissue levels that can lead to a strong risk for breast cancer and reproductive cancers. While estrogen levels drop only 40-60%, at menopause progesterone levels may drop to near zero in some women, resulting in estrogen dominance and the array of symptoms that go with it. Supplementation of natural bio-identical progesterone has been shown to restore hormonal balance, especially during perimenopause and menopause.