The persistence of menstruation on birth control pills may be caused by the side effects of birth control pills, or a miscarriage when you were already pregnant before birth control, or a combination of diseases during birth control pills. It is recommended to clarify the causes, change the method of birth control, and if there is a disease, it needs to be treated aggressively. Common causes and treatments are as follows. First, the side effects of birth control pills oral contraceptive is a high content of estrogen, progesterone or estrogen-progestin combination, after taking the body to change the hormone levels, menstrual irregularities, can be manifested as increased menstrual flow, amenorrhea, menstrual flow or menstrual dribbling and so on, contraceptive metabolism is complete menstruation within a month to return to normal. Second, pregnancy after taking part of the contraceptive pill can lead to miscarriage, vaginal bleeding, check the blood HCG value can be diagnosed as pregnancy, generally do not do birth control treatment, the feasibility of abortion to terminate the pregnancy, plus purging to prevent infection. Combined diseases: 1, endometrial thickening: women of childbearing age, long-term anovulation, oligo-ovulation, long-term use of tamoxifen can be caused by abnormal vaginal bleeding, prolonged menstrual period, increased bleeding, non-menstrual bleeding, bleeding period can be treated by scraping the uterus to stop bleeding and take a biopsy of the tissues, and there is a tendency of malignant changes, it is recommended that the whole hysterectomy; 2, uterine fibroids: the cause of the pathogenesis of the disease is not known, and may be associated with hormone metabolism abnormalities Fibroids: the cause is unknown, can be related to hormone metabolism abnormalities, generally no abnormality, fibroid enlargement can appear vaginal irregular bleeding, dribbling, abdominal pain, anemia, etc., the use of mifepristone, tamoxifen can shrink fibroids, inhibit growth, too large or cause serious bleeding or lead to infertility of fibroids, the need for timely surgical elimination or hysterectomy. Precautions Contraceptive pills contain more estrogen, it is best not to take for a long time, after taking the pill may appear endocrine disorders, irregular menstruation, amenorrhea and other various situations, it is recommended to replace other contraceptive measures, such as condoms.