In 1947, DES finally gained FDA approval for prescription to pregnant women who had diabetes as a method of preventing miscarriages. This led to the widespread prescription of DES to all pregnant women.In 1971, the FDA recommended against the prescription of DES to pregnant women. As a result, DES then began to see a withdraw from the US market starting in 1972 and in the European market starting in 1978, but the FDA still did not withdraw its approval for the use of DES in humans.DES was classified as a Group 1 carcinogen by the International Agency for Research on Cancer. After classification as a carcinogen, DES had its FDA approval withdrawn in 2000. DES is currently only in use for veterinary practices and in research trials as allowed by the FDA.Medical Ethics
Medical Ethics in regard to the approval and use of Diethylstilbestrol have been dismissed because of the actions of the FDA and pharmaceutical companies that were making DES at the time of its use. The Vice President of the American Drug Manufacturers Association, Carson Frailey, was employed by drug companies creating DES in order to help get it approved by the Food and Drug Administration (FDA). Nancy Langston, the author of The Retreat from Precaution: Regulating Diethylstilbestrol (DES), Endocrine Disruptors, and Environmental Health, states that "Frailey persuaded fifty-four doctors from around the country to write to the FDA, describing their clinical experiences with a total of more than five thousand patients.
The recommended regimen started at 5 mg per day in the seventh and eighth weeks of pregnancy (from first day of last menstrual period), increased every other week by 5 mg per day through the 14th week, and then increased every week by 5 mg per day from 25 mg per day in the 15th week to 125 mg per day in the 35th week of pregnancy. DES was originally considered effective and safe for both the pregnant woman and the developing baby. It was aggressively marketed and routinely prescribed. Sales peaked in 1953. In the early 1950s, a double-blind clinical trial at the University of Chicago assessed pregnancy outcomes in women who were assigned to either receive or not receive DES. The study showed no benefit of taking DES during pregnancy; adverse pregnancy outcomes were not reduced in the women who were given DES. By the late 1960s, six of seven leading textbooks of obstetrics said DES was ineffective at preventing miscarriage.Despite an absence of evidence supporting the use of DES to prevent adverse pregnancy outcomes, DES continued to be given to pregnant women through the 1960s. In 1971, a report published in the New England Journal of Medicine showed a probable link between DES and vaginal clear cell adenocarcinoma in girls and young women who had been exposed to this drug in utero. Later in the same year, the FDA sent an FDA Drug Bulletin to all U.S. physicians advising against the use of DES in pregnant women.