It is better to have the IUD between 3-5 days after menstruation, but there are certain requirements when having the IUD, you should not have intercourse after menstruation to avoid the chance of unwanted pregnancy. Vaginal douching and vaginal medication should not be performed to avoid abnormalities in the laboratory test before the IUD, which may affect the laboratory results and lead to certain errors. Because of mycosis vaginalis, trichomonas vaginalis, bacterial vaginitis, direct IUI cannot be performed, but need to be treated for a period of time to avoid upstream infection, which may cause pelvic or uterine abscess. At the same time, you should not have intercourse within half a month after IUI after menstruation, and there will be a small amount of bleeding.