The Drugs We Gave to Prevent Miscarriage Caused Cancer
DES seemed safe. A negative trial was ignored for 18 years. The daughters paid the price.
Post 2 of 11 in the From Routine to Regret series. FromRoutineToRegret
In 1953, a randomized controlled trial demonstrated that diethylstilbestrol did not prevent miscarriage.
In 1971, physicians were still prescribing it.
In between, millions of women took a synthetic estrogen that would give their daughters clear-cell adenocarcinoma of the vagina, reproductive tract abnormalities, infertility, and increased rates of adverse pregnancy outcomes. Some of those daughters are still dealing with the consequences today.
The DES story is the most dramatic example of harm from a routinely prescribed obstetric medication. But it is not the only one. During the same era, we prescribed bromocriptine to suppress lactation in women who chose not to breastfeed. The drug caused postpartum strokes, seizures, and myocardial infarction. We gave prophylactic phenobarbital to prevent neonatal intraventricular hemorrhage. A definitive trial showed no benefit.
Three medications. All given routinely. All supported by physiological reasoning rather than randomized evidence. All causing harm that was predictable in retrospect and preventable at the time.
The pattern that connects them matters more than any single drug, because the pattern is still operating.
The DES Timeline
The story begins in 1948 when Olive Smith published data suggesting DES prevented pregnancy complications. Her work was observational, not randomized. But the biological rationale seemed sound: estrogen supplementation should support pregnancy maintenance.
By the early 1950s, DES was being prescribed to millions of pregnant women. It was considered safe, effective, and standard of care.
Then in 1953, Dieckmann and colleagues published a randomized controlled trial in the American Journal of Obstetrics and Gynecology. The trial was well-designed for its era. The conclusion was unambiguous: DES did not prevent miscarriage or any other pregnancy complication.
The trial was largely ignored.
Free Subscriber Bottom Line: Three medications prescribed routinely in obstetrics caused direct, measurable harm: DES caused cancer in the daughters of exposed women, bromocriptine caused postpartum strokes and seizures, and prophylactic phenobarbital for neonatal IVH provided no benefit. In each case, the evidence against the drug was available years before practice changed. The DES story, where a negative randomized trial was ignored for 18 years, remains the most consequential example of the evidence-to-practice gap in obstetric history.
Below, paid subscribers get: - The complete DES timeline from adoption through cancer discovery to long-term consequences - The bromocriptine disaster: FDA warnings, case series, and medicolegal fallout - Phenobarbital for neonatal IVH: the Shankaran trial that ended a practice - A comparative table of all three drugs with proposed mechanism, actual evidence, harm documented, and litigation exposure - The malpractice question: at what point does prescribing against evidence become negligence?
