Degeneration of uterine fibroids is a frequent complication in pregnancy, with red degeneration being the most prevalent form. In contrast, sarcomatous transformation of uterine fibroids during pregnancy is exceedingly rare. Fibroids exhibiting sarcomatous change are highly malignant and carry a significant risk of metastasis. When such transformation occurs during pregnancy, clinical manifestations are often nonspecific and may include rapid enlargement of the uterine mass, abdominal pain, and vaginal bleeding.Magnetic resonance imaging serves as the primary auxiliary diagnostic tool. Although miscarriage and preterm delivery are major obstetric complications of sarcomatous degeneration, most patients diagnosed in the late third trimester can achieve favorable fetal outcomes. It is very difficult to diagnose sarcomatous transformation of uterine fibroids during pregnancy, and the diagnosis is ofter confirmed only after cesarean section or vaginal delivery. Prompt surgical intervention for complete tumor resection, along with adjuvant radiotherapy or chemotherapy when indicated, is critical to optimizing maternal prognosis.