New Data on DES Exposure

It’s been suspected for some time that when a female fetus is exposed in utero to DES (the first synthetic form of estrogen)--because her mother happened to be prescribed this drug during pregnancy--that daughter may have an increased risk of getting breast cancer when she becomes an adult.

New research conducted at the National Cancer Institute (NCI) and published in the October 6, 2011, issue of the New England Journal of Medicine has confirmed this suspicion. That is, when female fetuses are exposed to DES in utero, as adults these women are at increased risk for cancer, as well as for quite a few other disorders and diseases.

Beginning in 1940, DES (diethylstilbestrol) was used clinically by physicians to prevent certain complications of pregnancy. In the 1950s, clinical studies showed that DES was useless for this intended purpose; however, it wasn’t until 1971 that the U.S. Food and Drug Administration sent out a warning to physicians that they must stop prescribing DES to pregnant women. Meanwhile, somewhere between 5 million and 10 million pregnant women had already received it.

So, what other medical disorders did the NCI study determine that “DES babies” could get as adults?

• a 2-fold higher risk of infertility (1 in 5)
• a 5-fold higher risk of having a preterm delivery (1 in 3)
• more than twice the risk (1 in 25 by age 55) of developing pre-cancer of the cervix or the vagina, or both
• and--hold on to your bra--an 80 percent greater chance (1 in 50) of developing breast cancer after age 50.

The women participating in this important study were part of the NCI’s DES Follow-up Study, which was begun in 1992 and which is still going on today. These women will continue to be followed, so anticipate more information coming forth in the future regarding this long-term problem.