The causes of congenital hand deformities are medications taken by the mother during pregnancy, exposure to external radiation, and deformities formed during embryonic development. Most hand deformities are caused by congenital genetic factors, and mothers should avoid taking drugs and exposure to radiation during pregnancy to prevent congenital hand deformities. Congenital hand deformities are potentially hereditary to the offspring, because all congenital hand deformities form deformities during the embryonic period and defective genes are left in the body, and the offspring also have the condition of producing congenital hand deformities.