Brown discharge during pregnancy may be a normal physiological phenomenon, but it may also be caused by preeclampsia, ectopic pregnancy and other reasons. 1. Physiological phenomenon: some women in the early stages of pregnancy, when the gestational sac is in the bed, may cause a small amount of bleeding in the bed, manifested as brown discharge, is a normal physiological phenomenon. 2. Pre-eclampsia: Usually, pre-eclampsia is characterized by a small amount of vaginal bleeding, i.e. brown discharge, which may be accompanied by abdominal pain. 3. Ectopic pregnancy: Ectopic pregnancy is a common cause of brown vaginal discharge during pregnancy. Embryonic development is implanted in the uterus, but ectopic pregnancy means that the embryonic development is implanted in the fallopian tube, which is usually manifested by abdominal pain and vaginal bleeding. If brown discharge with abdominal pain occurs during pregnancy, you should go to a regular hospital in time to find out the cause of the disease and take targeted treatment under the guidance of a professional doctor.