The vaginal bleeding at the beginning of pregnancy without pain in the abdomen is considered to be: 1. caused by the embryo’s implantation of the fetal sac through the endometrium, the bleeding is dark brown and small in amount, which will be relieved by itself after a few days of observation and is a normal phenomenon. 2. caused by luteal hypoplasia and low progesterone level, the fetus stops developing or develops abnormally in the early pregnancy with symptoms of miscarriage, because the placental villi of the embryo are not well developed and have not completely Because the placental villi of the embryo are not fully developed and have not yet united with the endometrium, there is little bleeding and no abdominal pain. The main symptom of placenta praevia in late pregnancy is painless recurrent vaginal bleeding, which occurs after 28 weeks of gestation. 3. If you have inflammation of the vagina and cervix, polyps, malignant lesions, etc., the bleeding from the lesions is only bleeding without abdominal pain.