Hello, Welcome to HCM, I have read your query and duphaston tablets contain dydrogesterone, a synthetic derivative of the female sex hormone progesterone. It acts on the endometrium (lining of the uterus) converting the proliferating phase to the secretory phase. This causes the endometrium, which has thickened in response to oestrogen during the first half of the cycle, to stop growing and start secreting hormones and other proteins needed to maintain a pregnancy, if conception occurs; if not, levels of oestrogen and progesterone fall and the endometrium is shed (menstruation). The action of dydrogesterone in Duphaston helps in the treatment of infertility and spontaneous abortion (miscarriage) by stimulating the endometrium to prepare for a pregnancy and protect an existing pregnancy. Duphaston tablets act on the endometrium in all its locations to stop it growing, which alleviates symptoms of endometriosis including pain and bleeding. In miscarriages normally 10 mg twice daily on 11th-25th day of the cycle w/ continuous administration after conception and to continue until the 20th week of pregnancy, then reduce dose gradually. You should continue to take your tablets for as long as your doctor recommends, which may be for 5 days, or taken continually for several days a month and repeated each menstrual cycle for several months, as needed; or adviced by your gynaecologist. thanks