Vaginal bleeding during pregnancy is mainly caused by fertilized egg implantation, pre-eclampsia, ectopic pregnancy, gravida and cervical lesions. Therefore, if vaginal bleeding persists during pregnancy, you should visit a doctor for examination in time to avoid affecting the normal development of the fetus. 1. fertilized egg implantation: in some pregnant women, if capillary bleeding occurs during the process of fertilized egg implantation into the endometrium, it may cause bleeding, which is usually relatively small, without abdominal pain, and the bleeding will gradually disappear in 1-2 days. 2. pre-eclampsia abortion: early pregnancy with ovarian corpus luteum function Inadequate ovarian corpus luteum or fetal chromosomal abnormalities may easily lead to symptoms of pre-eclampsia miscarriage, which is manifested as brown or pink bloody discharge from the vagina, and if not treated in time, symptoms of lower abdominal pain and back pain will occur. Pregnant women should pay attention to rest, reduce activities, and carry out fetal preservation treatment under the guidance of doctors if necessary; 3, ectopic pregnancy: that is, ectopic pregnancy, commonly tubal pregnancy, with the growth of embryos, may cause local rupture haemorrhage, which can be accompanied by abdominal pain and can endanger the life of the pregnant woman, and the pregnancy should be terminated in time; 4, gravida: abnormal proliferation of placental chorionic trophoblast cells after pregnancy, which can manifest as abnormal vaginal bleeding, and should be treated by early The abnormal proliferation of placental trophoblast cells after pregnancy can be manifested as abnormal vaginal bleeding, which should be treated by surgery to clear the uterus as soon as possible; 5. placenta praevia: if the placenta abrupts, it can also cause bleeding, which usually requires bed rest and the application of drugs to suppress contractions under the guidance of a doctor; 6. cervical lesions: diseases such as chronic cervicitis, cervical polyps and cervical cancer can cause bleeding, which should be treated by a timely visit to a hospital to improve the examination and clarify the cause. Therefore, women in early pregnancy should pay attention to avoid overwork, smoking and drinking, external impact, ensure sufficient sleep and rest time, and seek medical attention when abnormalities occur to ensure the healthy development of the fetus.