Diethylstilbestrol (DES) is a synthetic form of the female hormone estrogen. It was prescribed to pregnant women between 1940 and 1971 to prevent miscarriage, premature labor, and related complications of pregnancy (1). The use of DES declined after studies in the 1950s showed that it was not effective in preventing these problems, although it continued to be used to stop lactation, for emergency contraception, and to treat menopausal symptoms in women (2).
In 1971, researchers linked prenatal (while in the womb, or in utero) DES exposure to a type of cancer of the cervix and vagina called clear cell adenocarcinoma in a small group of women (3). Soon after, the Food and Drug Administration (FDA) notified health care providers throughout the country that DES should not be prescribed to pregnant women (4). The drug continued to be prescribed to pregnant women in Europe until 1978 (5).
DES is now known to be an endocrine-disrupting chemical, one of a number of substances that interfere with the endocrine system to potentially cause cancer, birth defects, and other developmental abnormalities.
What is the cancer risk of people who were exposed to DES in utero?
The overall risk of cancer is not elevated in people whose mothers used DES while pregnant compared with the general population (6–8). However, females exposed to DES in utero, commonly called DES daughters, are at increased risk of several specific cancers.
Do the children of women who took DES have problems with fertility and pregnancy?
Several studies have found increased risks of premature birth, miscarriage, and ectopic pregnancy in females exposed to DES in utero.
Some studies suggest that the increased risk of infertility in DES daughters is due mainly to uterine or fallopian tube problems (14).
Males exposed to DES in utero have an increased risk of testicular abnormalities, including undescended testicles or development of cysts in the epididymis (15). There is also some evidence of increased risks of inflammation or infection of the testicles (15). However, DES sons do not have an increased risk of infertility, even when they have genital abnormalities (15).
What health issues might DES grandchildren have?
The data also suggested that infertility was greater among DES granddaughters than among unexposed women of the same age (25) and that they may have an increased risk of preterm delivery (24). However, this association is based on small numbers of events and was not statistically significant. Researchers will continue to follow these individuals to study the risk of infertility.
Recent studies have found that DES granddaughters and DES grandsons may have a slightly higher risk of cancer (26) and birth defects (27), including hypospadias in DES grandsons (28). However, because each of these associations is based on small numbers of events, researchers will continue to study these groups to clarify the findings.
How can people find out if they took DES during pregnancy or were exposed to DES in utero?
Women who think they used DES during pregnancy, or people who think that their mother used DES during pregnancy, can try contacting the health care provider or institution where they received their care to request a review of their medical records. If any medications were taken during pregnancy, obstetrical records could be checked to determine the name of the drug.
Each woman should discuss this question with her health care provider. There is no evidence that hormone replacement therapy is unsafe for DES daughters. However, some clinicians believe that DES daughters should avoid these medications because they contain estrogen (32).