Brown discharge at twelve weeks is considered to be caused by preeclampsia, low placenta status, gynecological inflammation and so on. 1. Pre-eclampsia: Pre-eclampsia may occur when a pregnant woman is strenuously active, suffers from mood swings, or has a serious uncontrolled disease, and a small amount of bleeding occurs at twelve weeks’ gestation. 2. Placenta hypoplasia: the placenta is attached to the lower part of the uterus and the edge is closer to the cervical opening, in this case there may be painless bleeding. 3. Gynecological inflammation: after pregnancy, the hormone level of the pregnant woman’s body undergoes a big change, the secretion will also increase, if there are some chronic reproductive organ diseases, such as cervicitis, vaginitis, there will be bleeding symptoms in acute attacks. Twelve weeks of brown discharge may also have other reasons, it is recommended to go to the hospital in a timely manner, improve the examination to clarify the cause of the disease, under the guidance of the doctor to give targeted treatment or treatment.