Epidemiology of gestational trophoblastic disease.

The epidemiology of gestational trophoblastic disease is not well understood. Methodologic problems with published reports limit the interpretation of incidence data, although the frequency of hydatidiform mole appears to be about one per 1000 pregnancies. No consistent temporal trends in rates of either hydatidiform mole or choriocarcinoma are evident. Hydatidiform mole appears to be caused by abnormal gametogenesis and fertilization. Age, ethnicity, and a history of hydatidiform mole appear to be important risk factors for hydatidiform mole. Age, ethnicity, a history of hydatidiform mole or fetal wastage, and ABO blood group interactions appear to be important risk factors for choriocarcinoma. Future studies should focus on the mechanisms by which these risk factors influence gametogenesis, fertilization, and malignant transformation of trophoblastic tissue.