Bleeding at 4 weeks of pregnancy may be caused by non-disease factors, or may be caused by diseases such as preterm miscarriage and ectopic pregnancy. Once the symptoms of vaginal bleeding appear, you should immediately go to the hospital for a complete examination and give reasonable treatment to ensure the normal progress of pregnancy. I. Non-disease factors: 1. Hormonal changes: After pregnancy, the estrogen and progesterone in the body change greatly, and a few pregnant women may have symptoms of vaginal bleeding due to hormonal fluctuations. Generally, no special treatment is needed. You can observe it first, strengthen your diet and regular work and rest; 2. Other: such as overexertion, or when sex occurs in the early stage of pregnancy, it may affect the embryo development and lead to the symptoms of vaginal bleeding. 2. Disease factors: 1. Pre-eclampsia: Patients experience vaginal bleeding, which is usually small, often dark red or bloody leucorrhea, accompanied by mild lower abdominal pain or low back pain of different degrees. Bed rest and strict prohibition of sexual intercourse are recommended, and progesterone, folic acid and multivitamins can be appropriately supplemented to maintain pregnancy; 2, ectopic pregnancy: if a pregnant woman has vaginal bleeding accompanied by pain and swelling in one side of the abdomen, it may be due to ectopic pregnancy, which can be diagnosed by gynecological ultrasound and usually requires surgical treatment to avoid greater damage; 3, biochemical pregnancy: that is, the fertilized egg does not successfully return to the uterus to be laid, and with The miscarriage is associated with menstruation. It is recommended to strengthen observation to ensure clean abortion to avoid residual pregnancy; 4. Cervical diseases: such as cervical inflammation, polyps, tumors, etc., may cause vaginal bleeding in pregnant women. It is recommended to make a clear diagnosis and choose symptomatic treatment such as observation, medication and surgery under the guidance of a doctor.