Subchorionic hemorrhage is a specific condition that occurs in women during pregnancy. The main causes of subchorionic hemorrhage are: 1) abnormal chromosomes carried by the egg and sperm during the formation of the fertilized egg, resulting in abnormal development of the embryo and causing subchorionic hemorrhage; 2) infection by special viruses or drugs that affect the development of the embryo during pregnancy, resulting in abnormal development of the embryo and causing subchorionic hemorrhage; 3) poor ovarian function during pregnancy and insufficient progesterone levels, which can also cause subchorionic hemorrhage. The lack of progesterone level can also cause subchorionic hemorrhage. 4, women who do not pay attention to rest and recuperation during pregnancy, resulting in excessive physical exertion, strenuous exercise or heavy physical labor, etc., may cause this phenomenon.