Brown discharge in pregnancy may be caused by spontaneous abortion, ectopic pregnancy, cervicitis and other reasons. 1. Spontaneous abortion: the common cause is chromosomal abnormality of the embryo or fetus, followed by the presence of luteal insufficiency of the mother, serious infections and other diseases, as well as smoking, alcoholism and other bad habits. It is also associated with chromosomal abnormalities in the embryo and excessive exposure to radioactivity and chemicals during pregnancy. The main manifestations are abdominal pain and vaginal bleeding, which manifests itself as a small amount of brown dribbling discharge. 2. Ectopic pregnancy: The causes of this disease include tubal inflammation, dysplasia, and uterine fibroids, endometriosis, pelvic inflammatory disease, etc. It is also related to smoking, mental stress, contraceptive failure and other factors. Typical symptoms are menopause, abdominal pain, vaginal bleeding, and brown discharge when bleeding is low. 3. Cervicitis: This disease is caused by infection of the cervix by Chlamydia trachomatis or Neisseria gonorrhea, and is related to factors such as imbalance of vaginal flora, hormone level disorders, and lack of attention to sexual safety. Some patients will experience symptoms such as increased vaginal discharge and abnormal bleeding, which manifests as brown discharge when vaginal bleeding is low. When brown discharge is found in pregnancy, you should go to the hospital in time to improve the relevant examination to clarify the specific cause.