Progesterone is a female hormone that is significant for the regulation of ovulation and menstruation. Whenever women who have not reached menopause yet begin to experience irregular periods, it means that progesterone is lacking from their body. Under such circumstances, this hormone is used to bring about menstrual periods in women. It is effective in avoiding overgrowth in the lining of the uterus in postmenopausal women, who are undergoing estrogen hormone substitution therapy. Your doctor may prescribe the amount of progesterone depending on your condition and prevailing medical history. The dosage differs from patient to patient, and there is no fixed or standard amount of dosage. Strictly stick to your prescribed amount of dosage.