On the first day of menstruation or other times during menstruation intercourse is very harmful to women’s health, easy to cause gynecological inflammation, endometriosis, the main hazards are the following: 1, easy to cause inflammation in the uterine cavity, menstruation endometrial peeling bleeding, so that the endometrial capillaries in an exposed state, if intercourse during menstruation easy to make pathogenic bacteria with sex invasion, menstrual blood is a good pathogenic bacteria The menstrual blood is a good medium for pathogenic bacteria to grow and multiply in the endometrium, causing endometrial inflammation and tubal inflammation; 2, causing vaginitis, the immunity is low during menstruation, and the pH of the vagina is easily changed due to the flushing of the menstrual blood, so the pathogenic bacteria can enter and cause vaginitis; 3, causing endometriosis, during sex the uterus is prone to contraction, which can easily lead to menstrual blood reflux causing endometriosis, in Sexual life is prohibited during menstruation.