Female physiological period is not recommended to cohabit, so as not to cause inflammation of the reproductive organs, menstrual disorders, endometriosis and so on. 1. Inflammation of the reproductive organs: female menstruation due to the expansion of the vagina and cervix, the endothelium shedding too late to repair, vaginal congestion, the nutritive effect of blood, etc., if physiological period of coitus will increase the chances of bacterial infections, but also make the blood backflow, increase the risk of infection, triggering a series of female genital inflammation, such as vaginitis, endometritis and pelvic inflammatory disease, etc.. 2. Irregular menstruation: women’s menstruation due to its special physiological response, the pituitary ovarian reproductive axis regulation, will trigger the heart and breasts and other parts of the discomfort symptoms, menstruation coitus will be due to emotional excitement lead to endocrine hormone disorders, resulting in menstrual irregularities. 3. endometriosis: physiological period of coitus will cause uterine contraction, may make the endometrium extrusion into the pelvic cavity, causing endometriosis, secondary cause dysmenorrhea or infertility. Therefore, it is not recommended to have intercourse during physiological period, pay attention to menstrual hygiene care, change underwear, sanitary napkins, pay attention to abdominal warmth, and feel comfortable.