The etiology of hemangioma is unknown. Studies have shown that the use of progesterone during pregnancy, undergoing chorionic villus sampling, hypertensive disorders during pregnancy, and low birth weight at the time of birth may be related to the formation of hemangiomas. It is believed that hemangiomas are a result of minor misconfigurations in the control gene segments during the embryonic development process, particularly during the early stages of vascular tissue differentiation. This leads to abnormal tissue differentiation at specific sites, eventually developing into hemangiomas. During the early months of embryonic development, from eight to twelve months, mechanical damage to embryonic tissue and local bleeding can cause some hematopoietic stem cells to be distributed among other embryonic cells, some of which differentiate into vessel-like tissues and ultimately form hemangiomas.