Diethylstilboestrol – A long-term legacy

Transgenerational effect of DES, i.e., children of sons or daughters of DES mothers, may have an epigenetic basis

2012 Study Abstract

Diethylstilboestrol (DES) is an endocrine disrupter which causes cancer in rodents.

It was prescribed in large amounts to treat women with gynaecological problems; some of the daughters of these women subsequently developed a rare cancer (vaginal clear cell adenocarcinoma) while genital abnormalities were found in some of the sons.

It was used for decades in livestock feed and this may have contaminated the food chain leading to the exposure of the more general population.

DES appears to cause epigenetic effects in animals and there is some evidence that this also occurs in man.

The mechanisms of carcinogenesis are complex and the effects are difficult to prove due to the background of dietary and environmental phyto- and xenooestrogens.

It has been suggested that, like other endocrine disrupters, DES may have acted as an obesogen in the human population.



DES Implications for the Third Generation

image of Grandson

The Health Effects of Diethylstilbestrol Revisited


“… DES has been associated with increased risk of reproductive tract tumors in third-generation mice, that is, mice whose grandmothers were exposed to DES. These tumors have included uterine adenocarcinomas and sarcomas and benign ovarian tumors in females as well as tumors in the rete testis in males.

By identifying persons with known exposure, as well as their children, potential participants for studies of the long-term effects of DES could also be identified. With appropriate samples and further research, greater knowledge of the health effects of DES on the children and grandchildren of women who took DES could be gained. Persons who may have been exposed to DES may find national websites and organizations (helpful to access current research and health information as it becomes available.”


  • The health effects of diethylstilbestrol revisited, Journal of obstetric, gynecologic, and neonatal nursing : JOGNN, NCBI PubMed, PMID: 16020417, 2005 Jul-Aug.

Increased Risk of Cancer in DES Grandsons and Granddaughters

Offspring of women exposed in utero to diethylstilbestrol (DES): a preliminary report of benign and malignant pathology in the third generation, 2008


Animal studies suggest that prenatal exposure to the synthetic estrogen diethylstilbestrol (DES) causes epigenetic changes that may be transmitted to the next generation. Specifically, these studies show an elevated incidence of reproductive tumors in the female offspring of prenatally-exposed mice.

We assessed cancer and benign pathology diagnoses occurring in the offspring of women whose prenatal exposure to DES (or lack of exposure) was verified by medical record. Our data arose from 2 sources: the mothers’ reports of cancers occurring in 8216 sons and daughters, and pathology-confirmed cancers and benign diagnoses self-reported by a subset of 793 daughters.

Although statistical power is limited, our data are consistent with no overall increase of cancer in the sons or daughters of women exposed in utero to DES. Based on pathology-confirmed diagnoses reported by the daughters, we saw no association between DES and risk of benign breast disease or reproductive tract conditions. Based on 3 cases, the incidence of ovarian cancer was higher than expected in the daughters of women exposed prenatally to DES.

Our data do not support an overall increase of cancer risk in the sons or daughters of women exposed prenatally to DES, but the number of ovarian cancer cases was greater than expected. While preliminary, this finding supports continued monitoring of these daughters.

Third-Generation Cohort

In 2001, the NCI assembled the third-generation cohort, consisting of the adult daughters (≥18 years of age) of DES-exposed and unexposed second-generation women.37 A review of parity records at all 5 study centers identified 763 exposed and 577 unexposed mothers of 966 exposed and 815 unexposed age-eligible daughters. About half of the mothers, 414 (54%) of the exposed and 297 (52%) of the unexposed, gave permission to contact 515 (53%) exposed and 383 (47%) unexposed daughters. The questionnaires, which queried daughters for hormonal and reproductive information, screening histories, and medical events (including gynecologic biopsies, breast biopsies, and cancer diagnoses), were returned by 793 (88%) of 898 daughters, including 463 (90%) exposed and 330 (86%) unexposed. Pathology reports were obtained to verify self-reported diagnoses and biopsies. A study-related review of histology slides confirmed 1 of 2 reported cases of borderline ovarian cancer. Slides were unavailable for the second case, which involved metastatic disease.

The confirmation of cancers occurring in the subset of adult daughters participating in the third-generation study was excellent. Of the 8 self-reported cancers, 7 (5 exposed, 2 unexposed) were confirmed by pathology; consent was not obtained to confirm a melanoma reported by an unexposed woman. For other conditions, confirmation of benign biopsies was reasonably good, generally exceeding 60%.

DES Follow-up Study Summary

Studies have shown a slightly increased risk of breast cancer in women who were given Diethylstilbestrol (DES) while they were pregnant. Their daughters, who were exposed to DES prenatally (before they were born), have an elevated risk of reproductive tract conditions, including a rare vaginal cancer. A question now being studied is whether DES health effects can be passed from the prenatally exposed women to their offspring (intergenerational transmission).

Studies in mice suggest that intergenerational transmission of DES health effects may be possible. Recent evidence indicates that prenatal exposure to DES may cause changes in the behavior of genes that influence hormones and the development of the female reproductive tract. These changes in gene behavior may be passed on to the next generation. Evidence for intergenerational transmission comes from mouse studies showing a higher number of reproductive tract tumors in the daughters of prenatally exposed female mice. We used the DES Follow-up Study data to assess whether cancer was more common in the offspring of women who were prenatally exposed to DES. Cancers affecting these offspring (the third generation) were identified using two approaches. First, we asked women participating in the DES Follow-up Study to report cancers diagnosed in their 8,216 third generation sons and daughters. Second, we asked 793 third generation daughters participating in the Third Generation Study to tell us about their cancers. We also asked the third generation daughters to tell us about their reproductive tract and breast biopsies. Next we confirmed the reported biopsies and cancers by checking the medical records of these third generation daughters.

Our results did not show an overall increase of cancer in the sons or in the daughters of prenatally DES-exposed women. However, based on only three cases, the number of ovarian cancers was higher than expected in the daughters of women exposed prenatally to DES. Because of the small number of cases, this result must be considered preliminary. The association may be a chance finding or may be due to the way in which the data were reported or collected. We did not find an association between DES and benign breast disease or reproductive tract conditions, but most of the women are too young for a meaningful assessment of these outcomes. Further follow-up is needed to assess whether prenatal DES exposure can affect the third generation in humans.


  • Full study (free access) : Offspring of Women Exposed In Utero to Diethylstilbestrol (DES): A Preliminary Report of Benign and Malignant Pathology in the Third Generation, Epidemiology doi: 10.1097/EDE.0b013e318163152a, March 2008.
  • Featured image credit oaks.journals.
  • NCIDES Follow-up Study Published Papers.

Birth Defects in the Sons and Daughters of Women who were Exposed in utero to Diethylstilbestrol (DES)

Possible association between the DES mothers exposure and birth defects in DES grandsons, DES granddaughters

2010 Study Abstract

Prenatal exposure to diethylstilbestrol (DES) is associated with adverse health outcomes, including anatomic anomalies of the reproductive tract in women and of the genitourinary tract in men. The mouse model, which replicates many DES-related effects seen in humans, suggests that prenatal DES exposure causes alterations that may affect the next generation of offspring.

Women participating in a large multi-center study of prenatal DES exposure were asked to report birth defects occurring among 4,029 sons and 3,808 daughters (i.e., the third generation). A subcohort of 793 third generation daughters were also queried for birth defects. We used logistic regression models to generate odds ratios and 95% confidence intervals for the association between prenatal DES exposure in the mother and birth defects in the offspring.

Based on the mothers’ reports, overall birth defects were elevated in the sons (OR = 1.53; 95% CI = 1.04, 2.23) and in the daughters (OR = 2.35; 95% CI = 1.44, 3.82). Most estimates of association were imprecise, but daughters appeared to have an excess of heart conditions (OR = 4.56; 95% CI = 1.27, 16.34.

Our data suggest a possible association between the mother’s prenatal DES exposure and birth defects in their offspring, particularly in daughters. We cannot, however, rule-out the possible influence of reporting bias. In particular, the exposed daughters’ elevated risk of cardiac defects may be due to the underreporting of these conditions by unexposed mothers.


  • Birth Defects in the Sons and Daughters of Women who were Exposed in utero to Diethylstilbestrol (DES), International journal of andrology, NCBI PubMed PMC2874639, 2010 April.
  • Featured image credit Nathan Dumlao.

Examination of multigenerational transmission of environmental associations

Toward an Emerging Paradigm for Understanding Attention-Deficit/Hyperactivity Disorder and Other Neurodevelopmental, Mental, and Behavioral Disorders

2018 Study Abstract

In Association of Exposure to Diethylstilbestrol During Pregnancy With Multigenerational Neurodevelopmental Deficits, Kioumourtzoglou et al use an approach that is as important as it is underused: an examination of multigenerational transmission of environmental associations. That approach may be the most important from an epidemiological perspective. They report that pollutant exposure to grandparents conveys a 30% increase in risk of ADHD in grandchildren. The findings are novel and contribute to this emerging shift in the understanding of mental and behavioral disorders such as ADHD. The size of the association, similar to many other concurrent risk factors for ADHD, is striking.

Although, as the authors note, the dosages of everyday individual environmental pollutants are generally lower (in developed countries at least) than the dosages of diethylstilbestrol they studied, today’s population is exposed to hundreds of poorly studied, neurodevelopmentally or hormonally active compounds, the interactions among which are unknown. Thus, the actual associations today are difficult to quantify.

The limitations in this study should not be overlooked—genetic associations were not able to be examined (so a genotype-environment correlation might partially account for findings), causality could not be evaluated because of the absence of F1 siblings, and ADHD assessment is limited in population studies. Their finding of a first trimester bias in the association, in particular, should be interpreted very cautiously; the incidence of ADHD in the second, third, and first trimester exposures were all higher than the unexposed group, and the statistical power to detect between-trimester associations was low. As the authors appropriately noted, further work on trimester-specific associations will be of interest. Finally, an epigenetic transmission is not the only possibility (because of third-generation oocyte exposure, as the authors noted), although epigenetic transmission by neuroactive chemicals to the third generation is demonstrated in nonhuman animals.


  • Toward an Emerging Paradigm for Understanding Attention-Deficit/Hyperactivity Disorder and Other Neurodevelopmental, Mental, and Behavioral Disorders, JAMA Pediatrics doi:10.1001/jamapediatrics.2018.0920, July 2018.
  • Featured image credit Jason Leung.

Do endocrine disruptors cause hypospadias?

Based on mouse data, exposure to DES raises the risk of genital malformation in subsequent generations. With a French database of 529 families with DES-exposed mothers, there was significant number of sons born to “DES-daughters” (8/97, P=0.02).

2014 Study Abstract

Endocrine disruptors or environmental agents, disrupt the endocrine system, leading to various adverse effects in humans and animals. Although the phenomenon has been noted historically in the cases of diethylstilbestrol (DES) and dichlorodiphenyltrichloroethane (DDT), the term “endocrine disruptor” is relatively new. Endocrine disruptors can have a variety of hormonal activities such as estrogenicity or anti-androgenicity. The focus of this review concerns on the induction of hypospadias by exogenous estrogenic endocrine disruptors. This has been a particular clinical concern secondary to reported increased incidence of hypospadias. Herein, the recent literature is reviewed as to whether endocrine disruptors cause hypospadias.

A literature search was performed for studies involving both humans and animals. Studies within the past 5 years were reviewed and categorized into basic science, clinical science, epidemiologic, or review studies.

Forty-three scientific articles were identified. Relevant sentinel articles were also reviewed. Additional pertinent studies were extracted from the reference of the articles that obtained from initial search results. Each article was reviewed and results presented. Overall, there were no studies which definitely stated that endocrine disruptors caused hypospadias. However, there were multiple studies which implicated endocrine disruptors as one component of a multifactorial model for hypospadias.

Endocrine disruption may be one of the many critical steps in aberrant development that manifests as hypospadias.


  • Full text (free access) : Do endocrine disruptors cause hypospadias?, NCBI PubMed PMC4708138, 2014 Dec.
  • Featured image credit Alex Hockett.

Hypospadias can be transmitted to the DES-exposed third-generation

Prenatal diethylstilbestrol induces malformation of the external genitalia of male and female mice and persistent second-generation developmental abnormalities of the external genitalia in two mouse strains

2014 Study Abstract

Potential trans-generational influence of diethylstilbestrol (DES) exposure emerged with reports of effects in grandchildren of DES-treated pregnant women and of reproductive tract tumors in offspring of mice exposed in utero to DES.

Accordingly, we examined the trans-generational influence of DES on development of external genitalia (ExG) and compared effects of in utero DES exposure in CD-1 and C57BL/6 mice injected with oil or DES every other day from gestational days 12 to 18. Mice were examined at birth, and on 5-120 days postnatal to evaluate ExG malformations. Of 23 adult (>60 days) prenatally DES-exposed males, features indicative of urethral meatal hypospadias (see text for definitions) ranged from 18% to 100% in prenatally DES-exposed CD-1 males and 31% to 100% in prenatally DES-exposed C57BL/6 males. Thus, the strains differed only slightly in the incidence of male urethral hypospadias. Ninety-one percent of DES-exposed CD-1 females and 100% of DES-exposed C57BL/6 females had urethral-vaginal fistula. All DES-exposed CD-1 and C57BL/6 females lacked an os clitoris. None of the prenatally oil-treated CD-1 and C57BL/6 male and female mice had ExG malformations. For the second-generation study, 10 adult CD-1 males and females, from oil- and DES-exposed groups, respectively, were paired with untreated CD-1 mice for 30 days, and their offspring evaluated for ExG malformations. None of the F1 DES-treated females were fertile. Nine of 10 prenatally DES-exposed CD-1 males sired offspring with untreated females, producing 55 male and 42 female pups. Of the F2 DES-lineage adult males, 20% had exposed urethral flaps, a criterion of urethral meatal hypospadias. Five of 42 (11.9%) F2 DES lineage females had urethral-vaginal fistula. In contrast, all F2 oil-lineage males and all oil-lineage females were normal.

Thus, prenatal DES exposure induces malformations of ExG in both sexes and strains of mice, and certain malformations are transmitted to the second-generation.


  • Full text (free access) : Prenatal diethylstilbestrol induces malformation of the external genitalia of male and female mice and persistent second-generation developmental abnormalities of the external genitalia in two mouse strains, NCBI PubMed PMC4254634, 2014 Oct.
  • Featured image credit figure/F1.

Testicular dysgenesis syndrome and the estrogen hypothesis: a quantitative meta-analysis

Some extreme positive risk ratios were reported after what is commonly referred to as “third-generation exposure” to DES

2008 Study Abstract

Male reproductive tract abnormalities such as hypospadias and cryptorchidism, and testicular cancer have been proposed to comprise a common syndrome together with impaired spermatogenesis with a common etiology resulting from the disruption of gonadal development during fetal life, the testicular dysgenesis syndrome (TDS). The hypothesis that in utero exposure to estrogenic agents could induce these disorders was first proposed in 1993. The only quantitative summary estimate of the association between prenatal exposure to estrogenic agents and testicular cancer was published over 10 years ago, and other systematic reviews of the association between estrogenic compounds, other than the potent pharmaceutical estrogen diethylstilbestrol (DES), and TDS end points have remained inconclusive.

We conducted a quantitative meta-analysis of the association between the end points related to TDS and prenatal exposure to estrogenic agents. Inclusion in this analysis was based on mechanistic criteria, and the plausibility of an estrogen receptor (ER)-alpha-mediated mode of action was specifically explored.

We included in this meta-analysis eight studies investigating the etiology of hypospadias and/or cryptorchidism that had not been identified in previous systematic reviews. Four additional studies of pharmaceutical estrogens yielded a statistically significant updated summary estimate for testicular cancer.

The doubling of the risk ratios for all three end points investigated after DES exposure is consistent with a shared etiology and the TDS hypothesis but does not constitute evidence of an estrogenic mode of action. Results of the subset analyses point to the existence of unidentified sources of heterogeneity between studies or within the study population.


  • Full study (free access) : Testicular dysgenesis syndrome and the estrogen hypothesis: a quantitative meta-analysis, NCBI PubMed PMC2235228, 2008 Feb.
  • Featured image credit Arthur Osipyan.

Risk factors for hypospadias

The associations found in this study support the hypothesis that genetic predisposition, placental insufficiency, and substances that interfere with natural hormones play a role in the etiology of hypospadias

2007 Study Abstract

Despite being one of the most common congenital defects in boys, the etiology of hypospadias remains largely unknown. In this case-referent study, we evaluated a wide spectrum of potential risk factors for hypospadias. Cases were identified from the hospital information system, and referents were recruited through the parents of the cases. Both parents of cases and referents completed written questionnaires that they received through the mail. Logistic regression analyses were used to assess the independent contribution of different factors to the risk of hypospadias. The final database included 583 cases and 251 referents.

Hypospadias more often occurred in children whose father had hypospadias (OR=9.7; 95%CI: 1.3-74.0) and in children with a low birth weight (OR=2.3; 95%CI: 1.2-4.2). Indications for elevated risks were found when mothers were DES-daughters (OR=3.5; 95%CI: 0.8-15.6), fathers were subfertile (OR=1.8; 95%CI: 0.7-4.5), the parents had undergone fertility treatment (OR=2.3; 95%CI: 0.9-5.8), and in twin or triplet pregnancies (OR=2.0; 95%CI: 0.8-5.1). Maternal use of iron supplements (OR=2.2; 95%CI: 0.8-6.0), maternal smoking (OR=1.5; 95%CI: 1.0-2.4), paternal prescriptive drug use (OR=2.6; 95%CI: 1.1-6.6), and paternal exposure to pesticides (OR=2.1; 95%CI: 0.6-7.1) during the 3 months immediately prior to conception or in the first trimester of pregnancy also appeared to increase the risk of hypospadias.

A strong indication for an increased risk of hypospadias was found among boys whose mothers were exposed to DES in utero – ‘DES-daughters’ – an association reported in a previous article by our group. In 2002, Klip et al. reported the prevalence ratio for hypospadias in sons of DES-daughters to be 21.3 (95%CI: 6.5–70.1), which was the first suggestion of a transgenerational effect of DES in humans. However, the association between intrauterine DES exposure and hypospadias was assessed in a cohort of women with fertility problems, who do not reflect DES-daughters in general. According to our findings, the excess risk of hypospadias appears to be of a much smaller magnitude. This may be explained by the differences in study design, and in the study population in particular, and probably results in a more valid risk estimate that is concordant with findings from a recent study in France. It is possible that DES-related pathology of reproductive structures in DES-daughters interferes with normal fetal development during pregnancy, but other explanations have been suggested as well.

We found no indication that DES-sons ‘transmit’ a predisposition to hypospadias to their sons. Our results also point towards an association between paternal subfertility and hypospadias.



Hypospadias in sons of women exposed to Diethylstilbestrol in utero

Increased risk of hypospadias in the DES grandsons, 2005


Diethylstilbestrol (DES) is a synthetic estrogen that was widely prescribed to pregnant women before 1971. DES increases the risk of breast cancer in women who took the drug and the risk of reproductive tract abnormalities in their offspring. Dutch investigators have reported a 20-fold increase in risk of hypospadias among sons of women who were exposed to DES in utero. We assessed this relation in data from an ongoing study of DES-exposed persons.

Several U.S. cohorts of women with documented exposure in utero to DES have been followed by mailed questionnaires since the 1970s. Comparison subjects are unexposed women of the same ages. In 1997, participants were asked about congenital abnormalities in their children. We calculated prevalence odds ratios for the risk of hypospadias in sons of exposed mothers relative to sons of unexposed mothers using generalized estimating equations to adjust for multiple sons per mother and controlling for maternal age at the son’s birth.

We obtained data from 3916 exposed and 1746 unexposed women. These women reported a total of 13 liveborn sons with hypospadias (10 exposed, 3 unexposed). The prevalence odds ratio for risk of hypospadias among the exposed was 1.7 (95% confidence interval = 0.4-6.8).

Our findings do not support a greatly increased risk of hypospadias among the sons of women exposed to DES in utero, as has been previously reported.


  • Hypospadias in sons of women exposed to diethylstilbestrol in utero, NCBI PubMed PMID: 15951681, 2005 Jul.
  • Featured image credit Bridget Coila.