Dydrogesterone is a progestin, a substance between natural progesterone and artificial progesterone, which is relatively simple to use and has a positive effect. In the early stages of pregnancy, oral dydrogesterone is mainly used to replenish progesterone, because one of the main causes of preterm miscarriage in the early stages of pregnancy is the lack of progesterone in the body. The purpose of oral dydrogesterone in the middle and late stages of pregnancy is to relieve the sensitivity of the uterus to contractin, which also has the same effect of preserving the fetus. In addition to this, dydrogesterone has a wide range of effects and can be used during non-pregnancy for progestational withdrawal bleeding or post-progestational half-cycle therapy, or even progestational full-cycle therapy, playing a very good role in treating abnormal uterine bleeding and preventing endometrial lesions.