Blood in the early stages of pregnancy may be caused by physiological reasons and pathological reasons such as preeclampsia and ectopic pregnancy. 1. Physiological reasons: some pregnant women in the early stages of pregnancy will have a small amount of vaginal bleeding at the time of fertilization of the egg, may also be accompanied by a slight pain in the lower abdomen, usually lasts for 3-4 days and will gradually return to normal, this is a normal physiological phenomenon, do not need special treatment. 2. Pathological causes: (1) preeclampsia: there will also be a small amount of vaginal bleeding symptoms, can also be accompanied by paroxysmal pain in the lower abdomen or lumbar pain, ultrasound examination is clear that the normal pregnancy, progesterone and blood HCG (human chorionic gonadotropin) levels can be detected decreased, need to comply with the doctor’s advice and actively preservation of the fetus treatment. (2) Ectopic pregnancy: the typical manifestation is a small amount of vaginal bleeding, accompanied by pain in one side of the lower abdomen, in the event of rupture of the pregnancy site may appear tear-like pain in the lower abdomen, ultrasonography, vaginal fornix puncture, blood HCG test to assist in the diagnosis. (3) Cervical polyps: can cause repeated small amounts of vaginal bleeding without abdominal pain, and can be diagnosed through gynecological examination and other assistance. When there is vaginal bleeding in early pregnancy, you need to go to the hospital in time in order to find out the cause as soon as possible and give treatment under the guidance of the doctor.