Pregnancy is a biological process that most women must go through, and the symptoms of vaginal bleeding during pregnancy plague many pregnant women. There are many causes of vaginal bleeding in early pregnancy, the most common of which is preeclampsia. Before a miscarriage occurs, the embryo is detached from the endometrial lining of the uterus, and a small amount of localized bleeding can occur. The causes of miscarriage can include fetal chromosomal abnormalities, fetal developmental abnormalities, and the mother’s own illnesses. In addition, low progesterone can also cause miscarriage. Progesterone is a hormone secreted by the corpus luteum of the ovary, which has the function of maintaining pregnancy hormones. If the progesterone in the body is too low, it can not support the embryo to continue the pregnancy, which can trigger a miscarriage. Finally, cervical polyps are also a common cause of vaginal bleeding in early pregnancy. Cervical polyp tissue is brittle and can bleed a small amount after activity. Regardless of the cause of vaginal bleeding in early pregnancy, it is important for the patient to visit the local hospital immediately to find out the cause of vaginal bleeding and take appropriate treatment according to the cause. To summarize, there are many causes of vaginal bleeding in early pregnancy, which need to be treated according to different causes.