You are not allowed to have intercourse on the last day of your period, even with a condom. Because menstruation is mainly caused by the shedding of the endometrium to cause bleeding, interspersed with the debris shed by the endometrium together to form menstruation, so the endometrium has trauma. On the last day of menstruation, the trauma of the endometrium has not been completely repaired, if intercourse is easy to bring external bacteria into the vagina. During menstruation, the mouth of the uterus is open, which can easily cause bacterial upward infection and endometritis. And the last day of menstruation, menstrual blood has not completely stopped, coitus is easy to cause accelerated blood circulation, resulting in excessive menstrual blood loss, affecting the health of women. It is also easy to cause cold in the uterus, dysmenorrhea, some patients will cause menstrual disorders and other symptoms. Generally need three days after the menstrual period, the uterine lining is completely repaired, this time is more suitable for coitus.