Sex on the sixth day of menstruation may be harmful to women’s health, because if the menstruation is not completely clean at this time to have sex, it may lead to pelvic inflammatory disease, menstrual disorders, endometriosis and other conditions, it is not recommended that women have sex during menstruation. 1. Pelvic inflammatory disease: generally women’s menstrual period of endometrial shedding, the mouth of the uterus is in an open state, the body’s resistance and immunity is relatively weak, this time to have sex may lead to bacterial invasion of the body, increase the chance of uterine infections, which may lead to the occurrence of pelvic inflammatory disease. 2. Menstrual disorders: some women’s menstrual periods are not completely clean on the 6th day of menstruation, and intercourse at this time is likely to cause congestion of the female reproductive organs, which may result in an increase in the amount of menstrual flow and prolongation of the menstrual period. 3. Endometriosis: When women are sexually aroused during intercourse, the uterus will generally contract, and at this time it may be easy for menstrual blood to flow back into the pelvic cavity, causing the endometrium to be planted, thus leading to endometriosis. Endometriosis is likely to affect pregnancy, so women are not advised to have intercourse during menstruation. It is recommended that women pay attention to vulvar hygiene during menstruation, eat a light diet, and if they feel unwell, they should go to the hospital in time and follow the doctor’s instructions for treatment.