Diethylstilbestrol (DES)

The largest number of DES prescriptions were ordered in 1953. By the middle 1950s, a series of studies suggested that DES did not actually help prevent miscarriages. Yet the drug continued to be given to pregnant women throughout the 1960s. Then, in the late 1960s, doctors noticed a series of cases of vaginal cancer in teenage girls and women in their twenties. This was troubling, because vaginal cancer had previously been seen primarily in much older women. By 1971, researchers had definitely linked DES to the vaginal cancer cases, and a report of the association appeared in the influential New England Journal of Medicine. That same year, the FDA prohibited the use of DES during pregnancy.

A total of about 600 cases of cancer of the cervix and vagina have been diagnosed in DES daughters. Daughters also are at higher risk of structural abnormalities of the reproductive tract and of poor pregnancy outcome. About one-half of all DES daughters experience an ectopic pregnancy, a premature birth, or a miscarriage. In addition, DES daughters are at a higher risk of infertility than women whose mothers did not take the drug.

The most common health problem reported by DES daughters is adenosis of the vagina. Adenosis is the abnormal development of glandular tissue. This occurs in 30% or more of DES daughters. About 25% of DES daughters have physical abnormalities of the cervix or vagina. Vaginal cancer occurs in less than 1 per 1,000 females whose mothers took DES.

Daughters of women who took DES are not the only ones at higher risk of health problems. Mothers who took DES face a slightly increased risk of breast cancer, and anecdotal evidence suggests that DES sons have a higher risk of testicular and semen abnormalities. Infertility and a higher risk of some types of cancer have also been reported among some DES sons.