Low, dark and prolonged menstrual bleeding may be related to preeclampsia, uterine fibroids, endocrine disorders and so on. 1. Pre-eclampsia: For women who are sexually active and do not use contraception in their sexual life, if the symptoms of prolonged, scanty and dark-colored menstrual bleeding occur, we should be alert to the possibility of pre-eclampsia. 2. Uterine fibroids: for women with uterine fibroids, due to the stimulation of the uterine lining by the level of estrogen and progesterone in the body, it may also lead to the symptoms of prolonged menstrual bleeding, low volume and dark color. 3. Endocrine disorders: some women often stay up late at night, work more intensively, and have too much mental tension, etc., which may lead to endocrine disorders and affect the hormone level in the body, thus leading to the decrease of menstrual flow, and the small amount of menstrual flow can’t be discharged out of the uterine cavity in time and will be manifested as the symptom of black color and long time. If the symptoms of low menstrual flow, darkness and long period occur regularly, it is recommended to carry out ultrasound of uterine adnexa, sex hormone six and other examinations in time to clarify the cause of the disease, and treat the cause of the disease.