Hydatidiform mole in the United States (1970-1977): a statistical and theoretical analysis.

The incidence of hydatidiform mole and some epidemiologic features of the disease in the United States were studied. Data for the present study were obtained from the Hospital Discharge Survey (1970-1977) of the National Center for Health Statistics. The estimated incidence of hydatidiform mole over the eight-year period was 108.4 per 100,000 pregnancies (SE = 10.3) or one case in every 923 pregnancies. There was an apparent increase in the incidence rate from 1970 to 1975, but the rate dropped slightly after 1975. The distribution of hydatidiform mole by maternal age showed the highest rate among women 35 years and older, and the second highest rate among women aged 15-19. The distribution by maternal age found for the entire sample was also apparent within each race category. Overall, black women appeared to have an incidence rate half that of white women. Regional differences in the United States were observed in spite of race and age adjustment. Existing studies are reviewed in light of morphologic and cytogenetic classification schemes and recent hypothesis for the androgenetic origin of hydatidiform mole. A fresh approach to the epidemiology of hydatidiform mole which combines epidemiologic and genetic studies is indicated.