Diethylstilbestrol (DES)

The development of DES by British scientist Edward Dodds (1899-1973) was one in a long line of twentieth century medical advances which reflected new understanding of the female reproductive system. While doctors had observed pregnancy, childbirth, miscarriages, and infertility for centuries, they did not gain an understanding of the hormonal functions behind these processes until the twentieth century. Through a series of discoveries, researchers learned that the process of pregnancy required a complicated series of hormonal triggers to occur successfully. They also learned that hormones were critical for the development of sexual characteristics in both men and women.

An early breakthrough was the successful isolation in 1923 of estrogen, the female sex hormone produced in men and women. Initially, the natural form of estrogen was extracted from animal ovaries, a process that was time-consuming and expensive. By 1936, the first synthetic estrogen was manufactured from plant steroids. In 1942, DES was approved by the U.S. Food and Drug Administration for use by menopausal women and for several other purposes. The drug was not approved for use by pregnant women until 1947, following reports that the drug could reduce the incidence of miscarriage.

At the time DES was first used for pregnant women, the substance was seen as a new weapon against infertility, stillbirths, and prematurity, according to a 1991 account by Edith L. Potter, a pathologist who specialized in obstetrics and gynecology during the time DES was prescribed. George and Olive Smith, the Harvard Medical School researchers who promoted the use of DES during pregnancy, believed that stillbirths and premature births were caused by a failure of the placenta to produce sufficient quantities of progesterone, Potter observes. They thought DES would relieve this condition, so that the pregnancies could be carried to term.

In the observation of practicing physicians, the substance appeared to cause no harm. Potter examined more than 10,000 infants who died of unrelated causes during this time, and she writes of seeing no apparent abnormalities due to DES. Problems did not become apparent until the DES infants were no longer infants.

Contemporary critics have faulted studies promoting DES for pregnant women because they did not include control groups—individuals given a placebo to help gauge the true effectiveness of DES. Without control groups, there was no scientific way to tell if the use of DES made women less likely to miscarry.