Dark brown vaginal discharge at 12 weeks of pregnancy may be associated with preeclampsia, ectopic pregnancy, gravida and other causes. 1. Pre-eclampsia: Mostly due to chromosomal abnormalities of the embryo or fetus, or maternal causes such as abortion. There may be a small amount of bleeding or vaginal bleeding with dark brown discharge. 2. Ectopic pregnancy: for example, tubal pregnancy, after the death of the embryo, causing irregular vaginal bleeding, dark red or dark brown in color, with a small amount. Dark brown vaginal discharge may also occur. 3. Staphylococcus: due to the proliferation of placental chorionic trophoblast cells after pregnancy, interstitial edema, and the formation of blisters of varying sizes, when the erosion of blood vessels, with the increasing ease of irregular vaginal bleeding, there will be a black discharge. When there is black-brown vaginal discharge in 12 weeks of pregnancy, it is recommended to consult a doctor in time, follow the doctor’s instructions to choose the appropriate examination, clarify the cause with the help of the doctor, and carry out targeted treatment or therapy.