DiEthylStilbestrol DES: a Cautionary Tale…

Disrupted Development: The Dangers of Prenatal Estrogen Exposure

DES: a Cautionary Tale


The drug diethylstilbestrol (DES) provides a striking andtragic example of the effects of prenatal exposures to chemicals that disrupt our hormones. DES was initially synthesized by a research team in London that had been searching for compounds that could be used for estrogen replacement during menopause, then referred to as deficiency disease. DES was approved by the FDA in 1941 to prevent miscarriages. It was prescribed to pregnant women for this purpose until 1971.

Early systematic studies failed to find evidence that DES was effective at preventing miscarriages but it continued to be prescribed to pregnant women. The wide use of DES created an accidental experiment that led to 5 to 10 million pregnant women – and the children born from those pregnancies – being exposed to this synthetic estrogen.

From 1966 to 1969, doctors at the Vincent Memorial Hospital in Boston noted a pattern of rare vaginal cancers in young women. These cancers were rare even in women over 50, and the hospital had never seen a single case of that specific type of cancer in younger women prior to 1966. The doctors conducted a study to determine similarities among the women, and found that the common thread was their mothers’ use of DES during their pregnancies. The doctors published a paper reporting
their findings in the New England Journal of Medicine in 1971, after which DES prescriptions were halted.

Since 1971, further research has linked prenatal DES exposure to a nearly two-fold increase in breast cancer among women over 40, and even higher rates among women over 50. Women who were presumed to have the highest exposures to DES (estimated based upon how much their vaginal cells were altered) had a higher risk of breast cancer.

The story of DES provides a cautionary tale about prenatal exposures to chemicals that can mimic the body’s own hormones. BPA is one such compound – In fact, BPA was even considered as an estrogen replacement by the same London laboratory that first created DES. As the DES story underscores, it can take decades to recognize the long-term health effects of early exposures to hormone-disrupting compounds in the general population, making it even more critical that we act on early warnings of harm. ”

Sources: Breast Cancer Fund’s report ” Disrupted Development: The Dangers of Prenatal BPA Exposure “, a comprehensive review of the scientific literature on prenatal BPA exposure, just-released.

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