Usually women menstruation is not recommended to have sex, but bed rest can be. If the menstruation come to bed with sex may have the following effects: 1, menstrual uterine bleeding, sex will have a strenuous exercise may lead to menstrual blood flow back into the pelvic cavity, thus leading to the possibility of endometriosis and later will have menstrual abdominal pain. 2, because of menstruation, then the vagina will bleed, sex may increase the pelvic cavity, vaginal infections. If you find abdominal pain after sex during menstruation, vaginal discharge after menstruation increased, yellow or even with the possibility of odor, it is recommended to be able to timely use of anti-infective treatment, but do not be too nervous too worried. Occasionally a menstrual intercourse sex does not cause obvious abdominal pain discomfort, there is no postmenstrual leukorrhea abnormality, then consider that this intercourse does not cause the possibility of infection.