Hydatidiform mole in Victoria: aetiology and natural history.

A retrospective study was made of 455 patients referred to the Hydatidiform Mole Register of the Royal Women's Hospital from 1973-1982 who fulfilled the criteria for diagnosis of hydatidiform mole. The incidence of hydatidiform mole was 1:1,357 livebirths in Victoria. Age greater than 40 years (P less than 0.001), nulliparity (P less than 0.005) and parity greater than 4 (P less than 0.001) were the only predisposing factors found. An association with artificial insemination with donor semen was also noted (P less than 0.025). The need for further treatment for persistent trophoblastic activity (13.6% of patients) was independent of the method of evacuation employed and of gestation at evacuation. Only 2 cases of histologically proven postmolar choriocarcinoma occurred, one of which was also the only death recorded from all patients registered following a molar pregnancy.