A group of diseases arising from pregnancy that are commonly associated with hyperplasia of trophoblasts (TROPHOBLAST) and markedly elevated human chorionic gonadotropin. They include hydatidiform mole, invasive mole (hydatidiform mole, invasive), placental-site trophoblastic tumor (trophoblastic tumor, placental site), and choriocarcinoma. These neoplasms have varying propensities for invasion and spread.