DES
Meaning of DES: A drug whose harms surfaced a generation later, in the children exposed before birth rather than in the women who were treated.
Definition of DES
DES, or diethylstilbestrol, is a synthetic estrogen that was prescribed to pregnant women in past decades in the belief that it prevented miscarriage. It did not, and it was later shown to harm the children exposed to it before birth. Its significance now is as an exposure recorded in a medical history rather than as a treatment.
Why was it given, and why did that stop?
Diethylstilbestrol is not a steroid and is not the estrogen the body makes, but it acts on the same receptors and is absorbed well when swallowed, which made it cheap and convenient to prescribe. It was given widely during pregnancy on the theory that supplementing estrogen would prevent miscarriage and premature birth. Controlled study eventually showed it did not do this. It was then linked to a very rare cancer appearing in young women whose mothers had taken it, and use in pregnancy ended.
What made the pattern so striking was the timing. The women who swallowed the tablets were largely unaffected at first, and the damage showed up only when the next generation reached adolescence and early adulthood, decades after the exposure itself.
Who is affected, and how?
| Group | What has been established |
|---|---|
| Women who took DES while pregnant | A modestly increased risk of breast cancer |
| Daughters exposed before birth | Clear cell adenocarcinoma of the vagina and cervix, a cancer otherwise almost unheard of at young ages; structural differences of the cervix, uterus and fallopian tubes; higher rates of infertility, ectopic pregnancy and preterm birth |
| Sons exposed before birth | Benign differences of the genital tract, including cysts of the epididymis and undescended testicle |
The vaginal and cervical tumor is a clear cell carcinoma, named for how the cells appear under the microscope, and its concentration in this one exposed group is what made the connection detectable at all.
Why does it still appear in records?
Because effects emerged so long after exposure, a DES history remains relevant across a whole lifetime and belongs in a family medical history as well as a personal one. The episode also changed how drugs are treated in pregnancy generally: it is the clearest demonstration that a substance can pass the placenta and alter the development of tissues that will not be tested for many years, and it reshaped both regulatory practice and the caution applied to prescribing during pregnancy.
Also known as
Used in a sentence
The patient's history included in utero DES exposure, which was noted given its association with later reproductive tract findings.
Good to know
DES exposure carries separate risks for the woman who took the medication during pregnancy and for a child exposed before birth, so both generations are considered when a DES history is documented.