Biochemical pregnancy bleeding for 20 days may be due to intrauterine infection, poor uterine recuperation, gynecological diseases and other reasons. 1. Uterine infection: If you have intercourse too soon after a biochemical pregnancy or if you suffer from cervicitis, vaginitis and other diseases, it may lead to retrograde pathogenic bacteria, resulting in infection of the uterine cavity and abnormal bleeding, which may be accompanied by pain in the lower abdomen, vaginal discharge of blood with a bad smell and other symptoms. 2. Poor uterine regeneration: some women may suffer from poor uterine regeneration after a biochemical pregnancy due to strenuous exercise, malnutrition, overwork, and mental stress, which may lead to poor uterine regeneration, which may be manifested as incessant bleeding after a biochemical pregnancy. 3. Gynecological diseases: For those who suffer from cervical diseases, pelvic tumors, gynecological endocrine abnormalities and other gynecological diseases, it may also lead to prolonged vaginal bleeding. Bleeding for 20 days after a biochemical pregnancy is an abnormal phenomenon, it is recommended to go to the hospital in time for ultrasound of uterine adnexa, blood human chorionic gonadotropin and other items, to clarify the cause of the disease, and then deal with the cause of the disease.