Diethylstilbestrol in pregnancy. Frequency of exposure and usage patterns

In view of the reported association between exposure in utero to diethylstilbestrol (DES) and clear-cell adenocarcinoma of the vagina, data on the prenatal use of DES in some 51,000 pregnancies in 12 hospitals between the years, 1959 and 1965, were examined. Among these women, in whom prenatal drug exposure was carefully documented, there was considerable variation in DES usage, the frequency being highest in the Boston Lying-In Hospital (exposure in 1.5% of pregnancies) and the Children's Hospital, Buffalo (exposure in 0.8% of pregnancies). Data from two marketing research sources were used to estimate DES usage in the United States. It is calculated that a maximum of 50,000 liveborn females per year, born between 1960 and 1970, were exposed to DES in utero, while the most likely estimate is in the range 10,000 to 16,000.