An important study by researchers with the National Cancer Institute DES Follow-up Study was published in the October 2011 New England Journal of Medicine. It shows why so many DES Daughters have had difficulties seeing their pregnancies through to delivery.
Structural Changes of the Reproductive Tract
DES Daughters have an increased incidence of structural changes in their reproductive organs, among them a T-shaped uterus (See illustration below). The uterine lining of a T-shaped uterus appears to be the same as for an unexposed woman, so researchers suggest the fundamental difference (except for the shape) is in the underlying structure of the fibromuscle. Of note is that pregnant DES Daughters with a T-shaped uterus and those with a normally shaped uterus are both at increased risk for premature delivery.
Prenatal DES exposure can adversely affect the shape and functioning of virtually the entire reproductive tract, including the vagina, cervix, uterus, fallopian tubes, and ovaries. Some DES Daughters report having an incompetent cervix, which can be the cause for second-trimester pregnancy losses.
DES Daughters have an increased risk for infertility with studies showing a 33% infertility rate after 12-months for DES Daughters compared with a 15.5% rate for unexposed women in the same time frame. Generally, infertility treatments for DES Daughters are the same as for other women. However, once achieving a pregnancy DES Daughters should be given high risk prenatal care. That means having more frequent exams and careful monitoring for possible early contractions.
Of note is that when a DES Daughter first suspects she is pregnant she should visit her physician for a blood test and perhaps an ultrasound to confirm the pregnancy is located in her uterus. See Ectopic Pregnancy below.
DES Daughters should have early confirmation of pregnancy to be certain the fetus is not developing outside of the uterus. Among DES Daughters ectopic (or tubal) pregnancies occur about 14.6% of the time compared with less than 3% of the time in pregnancies of unexposed women. An ectopic pregnancy is a potentially life-threatening condition that is best handled when identified early.
Miscarriage and Preterm Labor
Because of the increased risks for these problems, all DES Daughters, even if they’ve had previous normal pregnancies, require high-risk obstetric care – starting at the earliest stage of pregnancy.
Current research findings show DES Daughters experience preterm delivery at the not insignificant rate of 53.3% compared with 17.8% for unexposed women. Miscarriages have been shown to occur in 50.3% of DES Daughters with unexposed women experiencing them at a rate of 38.6%.
Most early miscarriages are not preventable. However, careful monitoring of the cervix as a “high-risk” patient is warranted.
To reduce the risk of late miscarriage or preterm pregnancy, a DES Daughter who is being treated as a “high-risk” obstetrics patient will learn to monitor for possible early contractions.
Understanding the cause of a threatened second trimester pregnancy loss is important. Some second-trimester losses occur in DES-exposed women because of incompetent cervices, while others are the result of premature labor. This is an important distinction, since treatments employed in these conditions are different. Sometimes a cerclage (stitch) is inserted to keep the cervix closed if an incompetent cervix is the problem. In the case of possible preterm labor the doctor may recommend bed-rest or drugs to suppress labor, and a cerclage would be of no use. Of course, DES Daughters are urged to accept medications cautiously and learn why they were prescribed, how they work and what side effects are known.
*DES Granddaughters according to a 2018 study, have higher incidence of preterm birth delivery. An article on a study which appeared in Reproductive Toxicology in December 2018 states that DES Granddaughters have a higher risk of irregular menstruation, of going at least six weeks without a period and of having a preterm birth delivery than other women in the population whose mothers were not DES Daughters. Members may login to see the article on this study in the Winter Voice 2020. DES Granddaughters should make their doctors aware of this if they are planning to become pregnant or are pregnant. They should receive high-risk obstetric care.
This form of high blood pressure and edema (fluid retention) during pregnancy happens to DES Daughters about 26.4% of the time versus 13.7% in unexposed pregnant women.