Q: I was exposed to DES during pregnancy. What should I do?

A: There is some evidence that the risk of tubal (ectopic) pregnancy, miscarriage, and premature delivery is increased for a DES-exposed daughter. Although most DES-exposed daughters do not experience DES-related problems during pregnancy, the doctor should be told of the DES exposure and should monitor the pregnancy closely.

DES (diethylstilbestrol) is a synthetic form of estrogen, a female hormone. It was prescribed between 1938 and 1971 to help women with certain complications of pregnancy. Use of DES declined in the 1960s after studies showed that it is not effective in preventing pregnancy complications. When given during the first five months of a pregnancy, DES can interfere with the development of the reproductive system in a fetus. For this reason, although DES and other estrogens may be prescribed for some medical problems, they are no longer used during pregnancy.

In 1971, DES was linked to an uncommon cancer (called clear cell adenocarcinoma) in a small number of daughters of women who had used DES during pregnancy. This cancer of the vagina or cervix usually occurs after age 14, with most cases found at age 19 or 20 in DES-exposed daughters. The upper age limit, if any, for DES-exposed daughters to develop this type of cancer is not known, and some cases have been reported in women in their 30s and 40s. The overall risk of an exposed daughter to develop this type of cancer is estimated to be approximately 1/1000 (0.1%).

Although clear cell adenocarcinoma is extremely rare, it is important that DES-exposed daughters continue to have regular physical examinations. Scientists found a link between DES exposure before birth and an increased risk of developing abnormal cells in the tissue of the cervix and vagina, although the significance of these findings is controversial. Physicians use a number of terms to describe these abnormal cells, including dysplasia, cervical intraepithelial neoplasia (CIN), and squamous intraepithelial lesions (SIL). These abnormal cells resemble cancer cells in appearance; however, they do not invade nearby healthy tissue as cancer cells do. These abnormal cellular changes usually occur between the age 25 and 35, but may appear in exposed women of other ages as well. Although this condition is not cancer, it may develop into cancer if left untreated. DES-exposed daughters should have a yearly Pap smear and pelvic exam to check for abnormal cells. DES-exposed daughters also may have structural changes in the vagina, uterus, or cervix. They also may have irregular menstruation and an increased risk of miscarriage, tubal (ectopic) pregnancy, infertility, and premature delivery.

There is some evidence that DES-exposed sons may have testicular abnormalities, such as undescended testicles or abnormally small testicles. The risk for testicular or prostate cancer is unclear; studies of the association between DES exposure in utero and testicular cancer have produced mixed results. In addition, investigations of abnormalities of the urogenital system among DES-exposed sons have not produced clear answers.

Women who used DES may have a slightly increased risk of breast cancer. Current research indicates that the risk of breast cancer in DES-exposed mothers is approximately 30% higher than the risk for women who have not been exposed to this drug. This risk has been stable over time, and does not seem to increase as the mothers become older. Additional research is needed to clarify this issue and whether DES-exposed mothers are at higher risk for any other types of cancer.

It has been estimated that 5-10 million people were exposed to DES during pregnancy. Many of these people are not aware that they were exposed. A woman who was pregnant between 1940 and 1971 and had problems or a history of problems during pregnancy may have been given DES or a similar drug. If you think you or your mother used a hormone such as DES during pregnancy, you could try to contact the attending physician or the hospital where the delivery took place to ask whether there is any record that you or your mother received DES. If any pills were taken during pregnancy, obstetrical records should be checked to determine the name of the drug. Mothers and children have a right to this information.

However, finding medical records after a long period of time may be difficult. If the doctor has retired or died, another doctor may have taken over the practice as well as the records. The county medical society or health department may be able to tell you where the records are. Some pharmacies keep records for a long time. If you know where the prescription was filled, you may be able to get this information. Military medical records are kept for 25 years. In many cases, however, it may be impossible to determine whether DES was used.

It is important for women who believe they may have been exposed to DES before birth to be aware of the possible health effects of DES and inform their doctor of their exposure. It is important that the physician be familiar with possible problems associated with DES exposure, because some problems, such as clear cell adenocarcinoma, are likely to be found only when the doctor is looking for them.

A thorough examination may include the following:

Pelvic examination - A physical examination of the reproductive organs. An examination of the rectum also should be done.

Palpitation - As part of a pelvic examination, the doctor feels the vagina, uterus, cervix, and ovaries for any lumps. Often palpation provides the only evidence that an abnormal growth is present. The cervical Pap test must be supplemented with a special Pap test of the vagina called a "four-quadrant" Pap test, in which cell samples are taken from all sides of the upper vagina. Iodine staining of the cervix and vagina - An iodine solution is used to temporarily stain the linings of the cervix and vagina to detect adenosis (a noncancerous but abnormal growth of glandular tissue) or other abnormal tissue.

Colposcopy - In colposcopy, a magnifying instrument is used to view the vagina and cervix. Some doctors do not perform colposcopy routinely. However, if the Pap test result is not normal, it is very important to check for abnormal tissue.

Biopsy - Small samples of any tissue that appear abnormal on colposcopy are removed and examined under a microscope to see whether cancer cells are present. Breast examinations - Thus far, DES-exposed daughters have not been shown to have a higher risk of breast cancer than unexposed daughters; however, they should follow the routine screening recommendations for their age group. A woman who took DES while pregnant (or suspects she may have taken it) should inform her doctor. She should try to learn the dosage, when the medication was started, and how it was used. She also should inform her children who were exposed before birth so that this information can be included in their medical records. DES-exposed mothers should have regular breast cancer screening and yearly medical checkups that include a pelvic examination and a Pap test.

DES - Exposed sons should inform their physician of their exposure and be examined periodically. While the level of risk of developing testicular cancer is unclear among DES-exposed sons, males with undescended testicles or unusually small testicles have an increased risk of developing testicular cancer, whether or not they were exposed to DES.

Is it safe for DES-exposed daughters to use oral contraceptives or hormone replacement therapy? Each woman should discuss this important question with her doctor. Although studies have not shown that the use of birth-control pills or hormone replacement therapy are unsafe for DES-exposed daughters, some doctors believe these women should avoid these medications because they contain estrogen. Structural changes in the vagina or cervix should cause no problems with the use of other forms of contraception, such as diaphragms or spermicides.