Changes in the incidence of molar pregnancies. A population-based study in Chiba Prefecture and Japan between 1974 and 2000

Abstract

The incidence of hydatidiform mole in Chiba Prefecture has become as low as that in Europe or the USA, and it is attributed to the decreasing incidence of complete mole. A number of environmental factors that prevent the ovulation of 'empty' oocytes might have contributed to the decreasing incidence of complete mole.