[Etiology: the etiology is not clear . Etiology of complete hydatidiform mole Epidemiology: the morbidity of hydatidiform mole is different in different area High risk factors 1. nourishing status, social economy 2. age: over 35 and 40 years old; below 20 years old 3. hydatidiform mole history: if a patient has the history of l or 2 times hydatidiform mole, then the morbidity of the hydatidiform mole when pregnant again is 1% and 15-20% respectively Genetic factors. 1. enucleate egg fertilization: chromosome karyotype of complete mole is diploid 90% is 46XX, 10% is 46XY[Etiology]:the etiology is not clear I.Etiology of complete hydatidiform mole Epidemiology: the morbidity of hydatidiform mole is different in different area. High risk factors: 1.nourishing status,social economy 2.age:over 35 and 40 years old;below 20 years old. 3.hydatidiform mole history:if a patient has the history of 1 or 2 times hydatidiform mole,then the morbidity of the hydatidiform mole when pregnant again is 1% and 15~20% respectively. Genetic factors: 1.enucleate egg fertilization:chromosome karyotype of complete mole is diploid ,90% is 46XX,10% is 46XY