WEDNESDAY, Oct. 5 (HealthDay News) -- Women whose mothers were
given the drug diethylstilbestrol (DES) during pregnancy are at
increased risk for fertility problems and cancer as they age, new
research shows.
This study from the U.S. National Cancer Institute "illustrates
that the effects of intrauterine exposure to biologically active
agents may take many decades to be fully appreciated or recognized
in humans," said Dr. William Rodgers, chairman of pathology at
Lenox Hill Hospital in New York City.
Use of DES -- the first synthetic form of estrogen -- to prevent
certain types of pregnancy complications began around 1940.
Research in the 1950s showed that DES didn't prevent these
complications, and in the late 1960s, exposure to DES in the womb
was linked to a rare cancer of the vagina (clear cell
adenocarcinoma) among daughters of women who took the drug.
In 1971, the U.S. Food and Drug Administration said DES should
not be given to pregnant women. But by that time, between 5 million
and 10 million moms-to-be and their babies had been exposed to the
drug.
In this study, NCI researchers looked at 4,600 women who were
exposed to DES in the womb and 1,900 who were not exposed to the
drug. They found that those with DES exposure were at increased
risk for 12 medical conditions, including a more than doubled risk
of infertility and a nearly fivefold increased risk of having a
preterm delivery.
Among DES-exposed women, one in five will have some level of
infertility, the study found. Of those who have at least one child,
one in three will have a preterm delivery.
The researchers also found that DES-exposed women are about 40
times as likely as unexposed women to develop clear cell
adenocarcinoma. However, the disease is still uncommon, with clear
cell adenocarcinoma occurring in one of 1,000 DES-exposed
daughters.
DES-exposed women are also more than twice as likely to develop
pre-cancerous cells in the cervix or vagina, and 80 percent more
likely to develop breast cancer after age 40.
By age 55, one in 25 DES-exposed women will develop abnormal
cellular changes in the cervix or vagina, and one in 50 will
develop breast cancer, according to the study.
"The risks were greatest in women with the largest DES exposure or who had changes in vaginal epithelium known to be caused by in utero exposure to DES," said Rodgers, who was not involved in the study. This strongly suggests that the DES exposure caused the reproductive problems, he said.
"Additional research will be needed to explain at a cellular level how DES exposure in utero produces these varied adverse reproductive outcomes," Rodgers said.
The study appears in the Oct. 6 issue of the
New England Journal of Medicine.
The researchers didn't look at men who were exposed to DES in
the womb, but previous studies indicate they may be at increased
risk for testicular abnormalities.
More information
The U.S. National Cancer Institute has more about
DES.