Hydatidiform mole in China: a preliminary survey of incidence on more than three million women.

A nationwide retrospective survey to determine the incidence of hydatidiform mole has been conducted in China since 1979 by inquiring into the history of past pregnancies. Up to the end of 1983, a total of 3 089 399 women with 10 929 354 pregnancies from 26 provinces, special municipalities and autonomous regions had been investigated. The overall incidence was one mole in 1238 pregnancies (0.81 per 1000 pregnancies). The incidence was higher in five provinces of south-east China than in other parts of the country and higher among the coastal people than inlanders. Ethnic comparisons were made between the major Han and three main minority groups. The incidence was higher among the Zhuang in Guangxi and the Mongolians in Inner Mongolia than among the Han living in the same areas. However, in Ningxia, the incidence among the Hui (Muslims) was almost the same as that of the Han. There was no significant difference in the incidence of hydatidiform mole between urban and rural residents.The traditional view that hydatidiform mole occurs much more frequently among women in China and other Asian countries has to be revised. The present study shows that the incidence in China is higher than that among Caucasian women in some European countries, but it is by no means as high as previously believed.