The best time to have an IUD is within 3-7 days of menstruation. The endometrium of the patient is the thinnest during this time, so the stimulation of the endometrium is relatively low when the IUD is placed. After the IUD is placed, the amount of bleeding is usually very small and the bleeding time is usually short, 3-5 days, so the damage to the patient is minimal. In addition, most of the patients who have the IUD placed during this time period do not have sex, and it is also more humane to tell the patient to refrain from sex before the IUD is placed, because the time required for the patient to refrain from sex is relatively short. In this way, the process of placing the IUD can avoid the occurrence of unwanted pregnancy, miscarriage, or ectopic pregnancy and other special circumstances.