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Diethylstilbestrol (DES), a synthetic estrogen, was prescribed to millions of
pregnant women in the United States from 1938 to 1971. Manufactured under many
different names (see
DES Names), the drug was marketed to prevent miscarriage or premature
birth by supplementing a pregnant woman's natural estrogen production. Research
noted that a decrease in urinary estrogen and progesterone preceded adverse
pregnancy outcomes. Thus it was postulated that administering estrogen would
induce placental hormone production; therefore, sustaining a viable pregnancy
(Smith, et al. 1948). Despite a landmark study in the early 1950s finding DES
ineffective in preventing miscarriage and premature birth (Dieckmann, et al.
1953) and subsequent research showing harm to the developing fetus, it was not
until 1971 that the Food and Drug Administration issued a warning about the
damaging effects of DES. In the United States, it is estimated that between 5
and 10 million people were exposed to DES during the years it was prescribed.
DES was similarly prescribed in several European countries from the 1950s into
the 1970s and may still be used in developing countries.
Although DES is no longer prescribed to pregnant women in the United States, DES
exposure continues to affect many lives:
DES is associated with a number of adverse health effects; some of those health
effects, including third-generation effects, are still unknown. Research to
date suggests that health risks for daughters born to DES mothers include:
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Increased risk of clear cell adenocarcinoma (CCA), a rare form of vaginal
cancer
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Structural differences in reproductive anatomy
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Increased risk of intraepithelial dysplasia and neoplasia
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Increased risk of infertility
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Increased risk of pregnancy complications
DES mothers, or women prescribed DES, appear to have a slightly increased risk
of breast cancer. DES sons—boys exposed to DES in utero—have an
increased risk of being born with genital abnormalities.
Today, clinicians may still encounter patients who are DES-exposed. It is
difficult to identify and confirm DES exposure in an individual. No simple test
can be given. There have been limited efforts to contact and subsequently
monitor the health of those exposed to DES, but researchers have been unable to
identify everyone. Many women and their children do not know whether they were
exposed to DES, and DES-related cancers often take many years to develop and
appear.
The ideal, but not always practical, way to identify DES exposed individuals is
to review complete obstetrical, hospital, or pharmacy records. This method can
identify mothers who have forgotten that they received DES or daughters whose
gynecologic examinations reveal no changes. However, in many cases, old records
have been destroyed or are incomplete; antenatal medications are not always
mentioned in hospital obstetrical records; and mothers of exposed children
cannot always be contacted.
Educational materials displayed in waiting rooms can alert individuals about
DES, but more important, clinicians need to ask pointed questions while taking
patients’ medical histories. Patients may not volunteer information about
DES exposure. Questions to ask patients include:
Did you or your mother:
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Take DES during pregnancy?
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Have problems carrying a pregnancy to term?
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Have a history of miscarriages for which medication was prescribed?
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Have a history of ectopic pregnancy?
Smith, O.W., et al. (1999) Diethylstilbestrol in the prevention and treatment of
complications of pregnancy. 1948. Am J Obstet Gynecol. 1999
Dec;181(6):1570-1.
Dieckmann, W. J., et al. (1953). Does the administration of diethylstilbestrol
during pregnancy have therapeutic value? American Journal of Obstetrics and
Gynecology, 66, 1062–1081.
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