Abstract:Threatened abortion complicated with intrauterine hemorrhage is a common disease during pregnancy.Its pathogenesis is related to the imbalance of maternal-fetal interface microenvironment and the obstruction of uterine spiral artery remodeling. Trophoblast cells are the outermost layer of the maternal-fetal interface microenvironment .Its proliferation, migration and invasion are closely related to normal pregnancy.It plays an irreplaceable role in immune tolerance and regulation, uterine spiral artery remodeling, and maintenance of maternal-fetal interface microenvironment.In recent years, trophoblast cells have become the main line of research in autoimmune diseases and other fields.Studies have found that it plays an important role in the diagnosis and treatment of threatened abortion complicated with intrauterine hemorrhage.This article reviews the research progress of trophoblast in the treatment of threatened abortion complicated with intrauterine hemorrhage.