The harm caused by having intercourse when a woman still has a little bit of menstruation can lead to uterine infections, pelvic inflammatory disease, and endometriosis. Because there is a small amount of vaginal bleeding during this period, the cervical opening is still loose, and during sex there is a possibility that the bacteria in the vagina may be infected due to the upward movement of the infection, which can lead to uterine infection or pelvic inflammation. It can also lead to endometriosis as the uterine contractions ectopic the exfoliated endometrium into the pelvic cavity or the uterine muscle layer, which can lead to dysmenorrhea or menstrual disorders in the future, which is not conducive to women’s health. It is best for women to have intercourse after three days of menstruation, as it will not adversely affect the woman’s body and will promote her health.