You can’t have sex during menstruation, even with a condom, as it can lead to infections and endometriosis. Women can’t have sex during menstruation, when the period is almost clean or when the period has just come, and even if you wear a condom, sex may increase the risk of infection and endometriosis. 1. Infection: menstrual blood is a good culture base for bacteria, wearing a condom during menstruation to have sex, it is easy to bring bacteria into the uterus and induce vaginitis, endometritis, cervicitis and other gynecological inflammatory diseases. 2. Endometriosis: The menstrual blood discharged during menstruation is caused by the shedding of the uterine lining. The shedding of the uterine lining may retrograde upwards with the process of sex, inducing endometriosis, which can’t be avoided even by wearing a condom. Therefore, women can not wear a condom during menstruation, need to be clean after menstruation and then have sex.