Pregnancy Drug DES, What You Should Know


Jan 10 2013 - 10:42am
Pregnancy Drug DES

More than half a century ago, millions of women were prescribed the pregnancy drug DES (diethylstilbestrol), and although it was eventually removed from the market for that purpose, its ghosts are still among us. A case in point is the recent trial in which four sisters with breast cancer sued one of the drug makers (Eli Lilly) because they said their cancer was caused by the DES their mother took while pregnant.

What should you know about DES?

DES is a synthetic type of estrogen that was prescribed to 5 to 10 million pregnant women between 1938 and 1971, according to the Centers for Disease Control and Prevention (CDC) for the purpose of preventing premature labor, miscarriages, and pregnancy complications. It was eventually found not to be effective for these purposes.

Although DES was no longer prescribed for pregnant women after 1971, some of the daughters and sons of those women appear to have been affected by the drug, and the impact may continue on for more generations. Here’s what researchers and other experts have to say about what is known—and uncertain—about DES.

DES and daughters of DES mothers
It’s been shown that DES interferes with the endocrine system. As an endocrine-disrupting substance, DES can cause birth defects, cancer, and other developmental problems. DES is most destructive when exposure occurs during development of a fetus (in utero).

A large study conducted by the National Cancer Institute and published in 2011 used data from three studies and followed them up long-term. The data were from 4,653 women exposed in utero to DES and 1,927 who were not exposed.

Overall, the researchers found that women exposed to DES (first figure) as compared to those not exposed (second figure) were at increased risk for the following problems:

  • Preterm delivery: 53.3% vs 17.8%
  • Spontaneous abortion: 50.3% vs 38.6%
  • Infertility: 33.3% vs 15.5%
  • Preeclampsia: 26.4% vs 13.7%
  • Ectopic pregnancy: 14.6% vs 2.9%
  • Stillbirth: 8.9% vs 2.6%
  • Grade 2 or higher cervical intraepithelial neoplasia: 6.9% vs 3.4%
  • Early menopause: 5.1% vs 1.7%
  • Breast cancer at age 40 or older: 3.9% vs. 2.2%

More information about DES

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