Brown discharge on the 42nd day of pregnancy may be caused by factors such as preeclampsia, ectopic pregnancy and gynecological diseases. 1. Pre-eclampsia: 42 days of pregnancy belongs to the early stage of pregnancy, the embryo is not stable, excessive exercise or sexual intercourse may cause pre-eclampsia, which will lead to the appearance of brown discharge from the lower body. 2. Ectopic pregnancy: after pregnancy, the existence of ectopic pregnancy, will also lead to 42 days pregnant with brown discharge, may continue to increase the amount of bleeding, accompanied by lower abdominal pain, serious cases will cause intra-abdominal hemorrhage. 3. Gynecological diseases: After pregnancy, the body immunity of pregnant women is reduced, improper daily care, may induce gynecological diseases, such as vaginitis, may lead to brown vaginal discharge, accompanied by vaginal itching, pain and other symptoms. Brown discharge on the 42nd day of pregnancy may be due to the presence of the above abnormalities or other reasons, it is recommended to seek timely medical examination and treatment to avoid adverse effects.