When progesterone is used to prevent pregnancy, the length of time a woman should take it should be determined by the development of the embryo, up to the third trimester of pregnancy. In the early stages of pregnancy, if a woman has a low level of progesterone and has a preterm miscarriage, she should be given progesterone medication for fetal preservation. If, after two weeks of treatment, the preterm miscarriage is relieved, the progesterone level in the body is normally elevated, the fetal heartbeat is good on ultrasound, the gestational sac is full, and the woman has no lower abdominal pain or vaginal bleeding, the progesterone medication can be gradually reduced. During the period of progesterone treatment, women should pay attention to proper rest, do not eat cold food, and can also give the kidney and fetus pill to assist treatment, the effect is also better.