DES (diethylstilbestrol) is a hormone that was prescribed for pregnant women in the 1950s and early 1960s. Many years later, doctors discovered that the daughters of the women who received DES were at high risk for a variety of problems, including infertility, premature labor, and cancer of the vagina and cervix.
In the 1950s and early 1960s, several drug companies claimed that DES (diethylstilbestrol) could prevent miscarriages. DES is a synthetic hormone, related to estrogen. Since up to 20% of all pregnancies end in miscarriage, this seemed like an important breakthrough and DES was prescribed for many women who had bleeding in early pregnancy. Ultimately, it was found to have no effect on miscarriages and the practice of prescribing DES was stopped in the 1960s. Almost 10 years later, the daughters of women who had taken DES during pregnancy began to develop unusual symptoms.
Doctors discovered that when these young women reached their teens, they were at higher risk for a variety of problems, including:
- clear cell adenocarcinoma of the vagina and cervix
- premature labor and other problems in pregnancy
It is estimated that five to 10 million people in the United States were exposed to DES between 1938 and 1971.
Causes and symptoms
DES has affected a very specific group of women. These are women who were exposed to DES in utero before 18 weeks of pregnancy. In other words, their mothers must have taken DES within the first four-five months of pregnancy. It is now known that the female reproductive organs are formed during that time. DES appears to interfere with proper growth and development of the uterus, cervix, vagina, and fallopian tubes. In 2003, new research showed that DES also was associated with increased risk of breast cancer.
In the early 1970s, there was an increase in a rare form of cancer, clear cell adenocarcinoma of the vagina and cervix. Up until that time, doctors had seen these cancers only in elderly women. Suddenly, young women who had the disease appeared.
This was so unusual that researchers studied these women to see if they had anything in common. After a great deal of questioning and examination, it was found that they all had one factor in common. All of the young women had been exposed to DES in utero in the early weeks of pregnancy.
Today, it is difficult to imagine how shocking this discovery was. Doctors had only recently recognized that medications and exposure to chemicals during pregnancy could cause birth defects. This was a birth defect that had gone undetected for almost two decades.
Since then, doctors have studied DES daughters very carefully. Fortunately, the risk of clear cell adenocarcinoma is actually quite low. In fact, it appears that if a DES daughter has not developed this cancer by age 30, she will not develop it. Since all DES daughters are now over age 30, there should be no further cases related to DES exposure. However, there are a number of other symptoms and problems associated with DES exposure.
- Cervix and vagina. DES daughters often have distinctive changes of the cervix and vagina that can be seen during a pelvic exam. These changes include a cervical hood (a vaginal fold draped over the cervix), cockscomb cervix (an abnormally shaped cervix), and adenosis (glandular cells normally located within the cervix that appear on the outside of the cervix and in the vagina).
- Fallopian tubes. Some DES daughters have fallopian tube abnormalities that lead to infertility.
- Uterus. Many DES daughters have a uterus that is abnormal in size and shape. The classic sign is the T-shaped uterus. In the normal uterus, the cavity (hollow space inside) is rounded. In a T-shaped uterus, the cavity is reduced to a thin T. The abnormal shape of the inside of the uterus makes it harder for a woman to get pregnant and leads to a higher risk of premature labor and birth.
Women who have been exposed to DES should have a pelvic exam at least once a year. In addition to the usual pelvic exam and Pap smear, DES daughters also should have Pap smears of the vagina and, if possible, colposcopy. During colposcopy, the doctor looks at the cervix and vagina through a special magnifying scope. In this way, tiny areas of abnormal cells can be seen. This procedure is easily performed in the doctor's office.
When DES daughters get pregnant, they may be at high risk for premature labor and birth and should be monitored very carefully.
Not all women who were exposed to DES develop problems in pregnancy. However, if problems like infertility or miscarriage occur, the doctor may recommend a special x-ray test to check the woman's fallopian tubes and uterus. This special test is called a hysterosalpingogram.
There is no treatment for the abnormalities of the fallopian tubes and uterus caused by DES exposure. Fortunately, there are treatments that can help with infertility and premature labor. Clear cell adenocarcinoma of the vagina or cervix must be treated with surgery and, possibly, chemotherapy.
Cervix— The opening at the bottom of the uterus.
Colposcopy— A special examination of the cervix using a magnifying scope. This is a procedure that can be done in the doctor's office.
Fallopian tubes— The tubes that carry the ovum (egg) from the ovary to the uterus.
Pap smear— A screening test for precancerous and cancerous cells on the cervix. This simple test is done during a routine pelvic exam and involves scraping cells from the cervix.
Kruse, Kelly, Diane Lauver, and Karen Hanson. "Clinical Implications of DES." Nurge Practitioner, July 2003: 26-29.
Morantz, Carrie, and Brian Torrey. "CDC Web site on Diethylstilbestrol." American Family Physician, November 15, 2003: 2088.