Hi, Susten contains progesterone which is a natural female sex hormone is used to treat menstrual and pregnancy related issues that are caused due to hormonal imbalance.it can be used as a hormone replacement therapy along with estrogen to relieve symptoms of menopause like hot flushes, night sweats, mood swings, vaginal dryness and reduced sex drive. Again, progesterone is important in the regulation of ovulation and menstruation. It is used to cause menstrual periods in women who haven t reached menopause but aren t having periods due to a lack of natural progesterone in the body. This medicine helps to prepare the uterus for pregnancy by causing the uterus lining to thicken. This increase the chance of a successful pregnancy. Take care. Hope I have answered your question. Let me know if I can assist you further. Regards, Dr. Zubayer Alam, General And Family Physician