The duration of dydrogesterone used for fertility treatment depends on the condition, and it is generally recommended to take the medication until clinical symptoms disappear, mostly around 12 weeks of gestation, which varies from person to person. Didrogestrel is a progestin that can be used for preterm miscarriage caused by ovarian luteal insufficiency and progesterone deficiency. Patients can take one tablet twice a day if they have symptoms of preterm miscarriage, or one tablet three times a day if they have significant abdominal pain or increased vaginal bleeding. The progesterone level should be monitored and the vaginal ultrasound should be reviewed regularly to check the development of the embryo. If the patient’s progesterone level is normal and the vaginal bleeding disappears after taking the medication, you can try to stop taking the medication after two days. In addition, patients should also pay attention to rest and avoid excessive mental stress during the course of fetal preservation treatment to avoid aggravating the symptoms of preterm abortion. If you are allergic to dydrogesterone, you should not take this drug for fetal preservation treatment.