Sudden bleeding in the third month of pregnancy is mostly an abnormal manifestation, generally considered as pre-eclampsia, ectopic pregnancy, gravida, cervicitis, etc. The most common one is pre-eclampsia. When bleeding occurs, first of all, pregnant women should not panic, tell their family members in time and go to the hospital for examination accompanied by their family members. 1. Pre-eclampsia: refers to a small amount of vaginal bleeding before 28 weeks of pregnancy, often dark red or bloody leucorrhea, without pregnancy discharge, followed by paroxysmal lower abdominal pain or low back pain. After treatment with birth control, if the symptoms disappear, the pregnancy can continue. If vaginal bleeding increases without timely treatment, or if lower abdominal pain increases, it may develop into unavoidable miscarriage. 2. Ectopic pregnancy: When the pregnancy capsule does not settle in the uterus, but outside the uterus, it will rupture the wall of the fallopian tube to a certain extent, resulting in vaginal bleeding, and corresponding measures should be taken according to the urgency of the condition. If the condition of vaginal bleeding is mild, medication or surgery can be used; 3. Cervicitis: Generally, there is a small amount of intermittent vaginal bleeding, and then gradually increase, and can repeatedly bleed a lot, it is recommended that the treatment be carried out as soon as possible when the body allows; 4. In this case, you can wait for the middle of pregnancy when the fetus is more stable, do cervical polyp removal.