Institutional belief · Obstetrics and drug regulation
DES for preventing miscarriage
Diethylstilbestrol (DES) was treated as an effective preventive treatment for miscarriage, premature labor and related adverse pregnancy outcomes.
1 episode
Current understanding
Current understanding
Controlled trials found no benefit from DES for preventing miscarriage or other adverse pregnancy outcomes, and prenatal exposure can cause serious long-term harms in offspring, including an increased risk of clear-cell adenocarcinoma and reproductive abnormalities. DES should not be used during pregnancy.
Institutional episode
United States
In 1947 the FDA approved DES for marketing as a miscarriage preventive, institutionalizing a treatment rationale that had been built largely on uncontrolled evidence. Better trials in the 1950s showed that the treatment did not prevent the pregnancy complications for which it was being prescribed, but use persisted. The decisive regulatory reversal came in 1971, when evidence linked prenatal DES exposure to a rare cancer in young women and the FDA warned clinicians not to prescribe DES during pregnancy.
Institutions
- U.S. Food and Drug Administration
Documented consequences
- Continued exposure of pregnant women and fetuses after controlled trials had failed to show the intended benefit
- Increased risk of clear-cell adenocarcinoma of the vagina and cervix among women exposed in utero
- Long-term reproductive and other health abnormalities among DES-exposed offspring
- A multigenerational drug-safety legacy requiring decades of follow-up and surveillance
Institutional machinery
DES had already been approved for other indications when the FDA approved new drug applications in 1947 allowing it to be marketed to prevent miscarriage. Controlled studies in the 1950s found that DES did not improve pregnancy outcomes, yet the drug continued to be prescribed during pregnancy for roughly two more decades. In 1971, after researchers linked in-utero DES exposure to a rare clear-cell adenocarcinoma in young women, the FDA notified physicians and required pregnancy to be listed as a contraindication.
Sources and what they establish
- DES Case Study — Women and Health ResearchNational Academies Press / NCBI Bookshelf
- Drug Therapeutics & Regulation in the U.S. — DiethylstilbestrolU.S. Food and Drug Administration
FDA history describing DES use as prophylaxis against preterm labor, miscarriage and other pregnancy complications, its spread into routine pregnancy use, and the agency's 1971 warning against treating pregnant women with DES.
- Selected Item from the FDA Drug Bulletin — November 1971 — Diethylstilbestrol Contraindicated in PregnancyU.S. Food and Drug Administration, reproduced in California Medicine via PubMed Central
Reproduction of the 1971 FDA Drug Bulletin announcing pregnancy as a contraindication after the association between maternal DES use and clear-cell adenocarcinoma in exposed offspring.
Last reviewed: 26/08/2026