The Diethylstilbestrol Legacy

A Powerful Case Against Intervention in Uncomplicated Pregnancy

2016 Report Abstract

Although the basic tenet of medicine is “First, do no harm,” history is filled with good intentions that were at best unhelpful and at worst harmful. Because medicine seeks to cure afflictions, there is an overwhelming desire on the part of health providers and patients to administer treatment. In certain settings, treatment can be reasonable despite a risk of adverse consequences: for example, if the disease is cured or its morbidity abated and the treatment consequences are less disabling than the disease itself.

In the absence of overt disease, the question of whether to apply an intervention is far more challenging. The safety of interventions must be weighed against the population’s level of risk, the morbidity and/or mortality associated with the disease, and the intervention’s efficacy (eg, BRCA1 mutation, mastectomy, reduced breast cancer risk). Interventions must meet an especially high standard of safety and efficacy when administered in low-risk populations or in settings in which the morbidity associated with the disease is minor. In the worst-case scenario, an intervention may be both ineffective for its primary purpose and cause iatrogenic illness.

The Diethylstilbestrol Legacy: A Powerful Case Against Intervention in Uncomplicated Pregnancy,
Pediatrics, November 2016, VOLUME 138 / ISSUE Supplement 1, Supplement_1/S42.abstract, November 2016.

Interventions in pregnancy are especially problematic because of the complex physiology of the condition and the possibility of causing short- and long-term adverse consequences in both the mother and her offspring. The continuing story of diethylstilbestrol (DES), a synthetic estrogen, shows the importance of caution when evaluating the merits of interventions involving pregnant women. With regard to DES, investigators believed that pregnancy loss was caused in part by a decrease in estrogen and that administering DES to pregnant women would help maintain a healthy pregnancy. Moreover, because endogenous estrogen concentrations increase dramatically during a healthy pregnancy, supplementation with DES was deemed harmless. During its early years of use, DES was administered to women with threatened pregnancy loss or a history of pregnancy loss. Eventually, DES was advertised to the medical community for “routine prophylaxis in ALL pregnancies” and administered to women with otherwise healthy pregnancies.

By the time DES was formally evaluated, it was standard of care in high-risk obstetrics practices. The first clinical trial to determine the efficacy of DES, reported in 1953, showed that DES did not improve pregnancy outcome. (Indeed, a subsequent reanalysis of the data revealed that DES increased the risk of spontaneous abortion, preterm birth, and neonatal death) Despite lack of evidence supporting a benefit, DES continued to be prescribed during pregnancy until 1971, when a small study showed a stunning 40-fold increase in the risk of clear cell adenocarcinoma (CCA) of the vagina and cervix in girls and young women who were prenatally exposed to DES. Several months later, the Food and Drug Administration issued a bulletin indicating that the use of DES was contraindicated in pregnancy. By then, however, millions of women, along with their sons and daughters, had been needlessly exposed.

In addition to the increased risk of CCA of the vagina and cervix, daughters exposed in utero to DES also suffered from an increased occurrence of reproductive tract abnormalities, infertility, and pregnancy complications; earlier menopause; twice the incidence of cervical dysplasia; and a possible elevated risk of breast cancer and continued increased risk of CCA in middle age. Recent preliminary data indicate the possibility of an increased risk of cardiovascular disease and diabetes in the prenatally exposed women. Mothers administered DES during pregnancy have an increased risk of breast cancer incidence and mortality. Sons who were exposed in utero have an increased risk of genitourinary defects and a possible increase in testicular cancer. The possibility of epigenetic transmission with consequent adverse outcomes in the offspring of prenatally exposed women is under investigation. Preliminary findings showed increased menstrual irregularity and a possible excess of ovarian cancer in very young women.

The link between prenatal DES exposure and subsequent adverse health outcomes, most of which are fairly common, may easily have escaped detection. The investigation of DES outcomes was initiated solely because a rare tumor occurred in a cluster of cases at an unusually young age, decades before the usual age of presentation. This historical example underscores the necessity of carefully weighing the risks and benefits of interventions in pregnancy and long-term monitoring of the health outcomes in mothers and offspring.

Whether and/or when to use pharmaceutical intervention in pregnancy continues to pose special challenges. At the present time, progesterone used to prevent pregnancy loss appears to be effective, although more data are needed. Thus far, there is little evidence of short-term adverse consequences for the offspring, but continued monitoring of mothers and offspring is warranted to identify any short- or long-term adverse effects. The use of progestins for luteal phase and early pregnancy support after in vitro fertilization is routine, and there are even fewer data on potential short- and long-term risks of this therapy. The tragic legacy of DES supports a cautious approach to the use of pregnancy interventions and assiduous appraisal of their effects.

Rebecca Troisi, Elizabeth E. Hatch, Linda Titus,
Reviewed by Dr Robert Hoover,

Click to download the full paper.

More DES DiEthylStilbestrol Resources

Evidence that bisphenol S crosses the human placenta

Common BPA alternative, BPS, crosses into placenta

Bisphenol S (BPS), found in baby bottles, personal care products and thermal receipts, is a replacement chemical for BPA and was introduced when concern was raised about possible health effects of that plastic compound.

As with BPA, there is evidence that BPS is an endocrine disruptor. Canadian and Chinese scientists have found the “first evidence” that BPS can cross the human placenta.

2017 Study Abstract

Human studies show associations between maternal bisphenol A (BPA) exposure and developmental effects in children, yet biomonitoring of BPA metabolites in maternal and fetal serum remains limited, and less is known for BPA alternatives. BPA-glucuronide, BPA-sulfate, and bisphenol S (BPS) were quantified in 61 pairs of maternal and cord sera from Chinese participants.

Bisphenol A Metabolites and Bisphenol S in Paired Maternal and Cord Serum, Environmental Science & Technology, DOI: 10.1021/acs.est.6b05718, January 22, 2017.

Total BPS was only detectable in four maternal (<0.03–0.07 ng/mL) and seven cord sera (<0.03–0.12 ng/mL), indicating low exposure but providing the first evidence that BPS crosses the human placenta. Total BPA metabolites in cord serum were significantly higher than in maternal serum (p < 0.05), suggesting that these may be formed in the fetus or cleared more slowly from the fetoplacental compartment. Unlike the pharmacokinetic results from controlled oral exposure studies in which BPA-glucuronide is the major BPA metabolite, here, BPA-sulfate was the dominant metabolite (GM: 0.06 and 0.08 ng/mL), significantly higher than BPA-glucuronide (GM: 0.02 and 0.04 ng/mL) (p < 0.01) in both maternal and cord sera. Moreover, the proportion of BPA-sulfate increased with total BPA.

These are the first human data for BPA metabolites in paired maternal and cord serum, and results suggest that the human fetus and pregnant mother have unique exposure to BPA metabolites. Direct analysis of BPA metabolites in serum provides complementary information for evaluating early life-stage exposure and risks of BPA.

Mother’s diet in pregnancy may have lasting effects for offspring

Visualizing Changes in Cdkn1c Expression Links Early-Life Adversity to Imprint Mis-regulation in Adults

A poor diet during pregnancy can cause biological changes that last throughout life, according to research from Imperial College London.

The study Visualizing Changes in Cdkn1c Expression Links Early-Life Adversity to Imprint Mis-regulation in Adults, published this week in the journal Cell Reports, showed that when pregnant mice were fed a diet deficient in protein this interfered with the expression of genes within the embryo that are known to be important for healthy growth.

The impact of adversity, such as a poor diet in early life, and whether this might cause lasting effects has long intrigued scientists. There have been suggestions that the children of women pregnant during famines, for example, may suffer harmful effects later in life. This new study offers a new way to visualise such effects and possible ways to counter these.

The researchers, at the Medical Research Council London Institute of Medical Sciences (MRC LMS), developed novel imaging techniques that enabled them to visualise genes as they were switched “on” or “off” in mouse embryos as they grew. This enabled the team to see exactly where alterations in response to maternal diet were happening and, crucially when during pregnancy key changes took place.

Understanding how genes are controlled and kept “on” or “off” is a relatively new field of science known as “epigenetics”. This is the first time such epigenetic effects have been visualised during development in this way, using a simple but powerful bioluminescent imaging approach.

The team attached enzymes from fireflies (luciferase) or bacteria (beta-galactosidase) onto the gene they were studying, and watched how this produced a glow as the gene was turned “on” in mice.

The research focused on a group of genes called “imprinted” genes, and on one in particular known as Cdkn1c. Imprinted genes are intriguing because although a copy of the gene is inherited from each parent, as usual, only one of these copies is active. The other copy is kept idle, or “silenced”. In the case of Cdkn1c, only the copy inherited from the mother is active.

Using their new visualising technique, the team showed that if a mouse carried the copy of the gene from the father, which is “silenced”, then it could not be seen. If they used either diet or drugs to re-activate it, they were able to see the gene glow. The researchers expect that this new way to “see” when imprinted genes are active or silent will prove valuable for many other scientists who are investigating epigenetic effects in our bodies.

Imprinted genes

Dr Mathew Van de Pette, a lead author based at the MRC LMS, said:

“There are around 100 imprinted genes, about 0.4% of the total in the genome, and most appear to have their greatest impact during pregnancy.
The pattern by which imprinted genes are ‘set’ in early life plays an important part in the development of healthy offspring. If a gene is ‘miss-set’ then problems may occur later.
We found that mice fed a low protein diet in pregnancy produced offspring in which the father’s copy of the gene became active and stayed that way. This demonstrates a clear link between early life adversity and later life outcomes.”

Professor Amanda Fisher, who led the study and is director of the MRC LMS, said:

“We were surprised that this change in diet permanently affected the expression of this imprinted gene.
Our work suggests there may be a window of vulnerability when diet can indeed have an effect, and that once these genes are set, they’re set for life.
The good news is that we’ve also shown that it’s possible to avoid this with a normal diet.”

Kate Wighton, Imperial College London newssummary, 03 February 2017.

High body mass index during pregnancy not associated with a long term risk of obesity in offspring

High Pregnancy BMI Not Linked to Offspring BMI

This new study looked at whether increased body mass index (BMI) in mothers while pregnant was causally associated with excess weight in offspring during childhood and adolescence. It also examined whether this effect was over and above the expected contribution of genes to being overweight.

2017 Study Abstract


It has been suggested that greater maternal adiposity during pregnancy affects lifelong risk of offspring fatness via intrauterine mechanisms. Our aim was to use Mendelian randomisation (MR) to investigate the causal effect of intrauterine exposure to greater maternal body mass index (BMI) on offspring BMI and fat mass from childhood to early adulthood.

Methods and Findings

Using Genetic Variation to Explore the Causal Effect of Maternal Pregnancy Adiposity on Future Offspring Adiposity: A Mendelian Randomisation Study, PLOS one,, January 24, 2017.

Image credit remon rijper.

We used maternal genetic variants as instrumental variables (IVs) to test the causal effect of maternal BMI in pregnancy on offspring fatness (BMI and dual-energy X-ray absorptiometry [DXA] determined fat mass index [FMI]) in a MR approach. This was investigated, with repeat measurements, from ages 7 to 18 in the Avon Longitudinal Study of Parents and Children (ALSPAC; n = 2,521 to 3,720 for different ages). We then sought to replicate findings with results for BMI at age 6 in Generation R (n = 2,337 for replication sample; n = 6,057 for total pooled sample).

In confounder-adjusted multivariable regression in ALSPAC, a 1 standard deviation (SD, equivalent of 3.7 kg/m2) increase in maternal BMI was associated with a 0.25 SD (95% CI 0.21–0.29) increase in offspring BMI at age 7, with similar results at later ages and when FMI was used as the outcome.

A weighted genetic risk score was generated from 32 genetic variants robustly associated with BMI (minimum F-statistic = 45 in ALSPAC). The MR results using this genetic risk score as an IV in ALSPAC were close to the null at all ages (e.g., 0.04 SD (95% CI -0.21–0.30) at age 7 and 0.03 SD (95% CI -0.26–0.32) at age 18 per SD increase in maternal BMI), which was similar when a 97 variant generic risk score was used in ALSPAC.

When findings from age 7 in ALSPAC were meta-analysed with those from age 6 in Generation R, the pooled confounder-adjusted multivariable regression association was 0.22 SD (95% CI 0.19–0.25) per SD increase in maternal BMI and the pooled MR effect (pooling the 97 variant score results from ALSPAC with the 32 variant score results from Generation R) was 0.05 SD (95%CI -0.11–0.21) per SD increase in maternal BMI (p-value for difference between the two results = 0.05). A number of sensitivity analyses exploring violation of the MR results supported our main findings. However, power was limited for some of the sensitivity tests and further studies with relevant data on maternal, offspring, and paternal genotype are required to obtain more precise (and unbiased) causal estimates.


Our findings provide little evidence to support a strong causal intrauterine effect of incrementally greater maternal BMI resulting in greater offspring adiposity.

Could prenatal test results decide for treatments to help reduce the effects of a genetic disorder?

Universal Haplotype-Based Noninvasive Prenatal Testing for Single Gene Diseases

Together, single-gene disorders are more common than Down’s syndrome. A fast test for genetic disorders means parents could learn about the future health of their baby as early as six weeks into pregnancy.

November 2016 Study Abstract

Researchers have developed approaches for the noninvasive prenatal testing of single gene diseases. One approach that allows for the noninvasive assessment of both maternally and paternally inherited mutations involves the analysis of single nucleotide polymorphisms (SNPs) in maternal plasma DNA with reference to parental haplotype information. In the past, parental haplotypes were resolved by complex experimental methods or inferential approaches, such as through the analysis of DNA from other affected family members. Recently, microfluidics-based linked-read sequencing technology has become available and allows the direct haplotype phasing of the whole genome rapidly. We explored the feasibility of applying this direct haplotyping technology in noninvasive prenatal testing.

Simple blood test can detect genetic diseases early in pregnancy, New Scientist, Magazine issue 3107, 7 January 2017.

Universal Haplotype-Based Noninvasive Prenatal Testing for Single Gene Diseases, American Association for Clinical Chemistry, DOI: 10.1373/clinchem.2016.268375, December 2016.

Icarus (Henri Matisse,1947) credit doomsteaddiner.

We first resolved the haplotypes of parental genomes with the use of linked-read sequencing technology. Then, we identified SNPs within and flanking the genes of interest in maternal plasma DNA by targeted sequencing. Finally, we applied relative haplotype dosage analysis to deduce the mutation inheritance status of the fetus.

Haplotype phasing and relative haplotype dosage analysis of 12 out of 13 families were successfully achieved. The mutational status of these 12 fetuses was correctly classified.

High-throughput linked-read sequencing followed by maternal plasma-based relative haplotype dosage analysis represents a streamlined approach for noninvasive prenatal testing of inherited single gene diseases. The approach bypasses the need for mutation-specific assays and is not dependent on the availability of DNA from other affected family members. Thus, the approach is universally applicable to pregnancies at risk for the inheritance of a single gene disease.

Highly toxic mercury and its compounds to be banned in children, pregnant and breastfeeding women’s dental amalgam

EU agrees dental amalgam ban in children, pregnant and breastfeeding women

Mercury and its compounds are highly toxic to humans, especially to pregnant women and the developing nervous system. Amalgam consists of 50% mercury, which under certain conditions can transform to neurotoxic methylmercury.

Brussels, 8 December 2016 – European civil society has endorsed this week’s provisional agreement by the three EU institutions (European Parliament, European Commission and the Council of the European Union) to ban dental amalgam fillings for children under 15 and for pregnant and breastfeeding women as of 1 July 2018.

The text, which must now be approved by both Parliament and Council, also requires each Member State to set a national plan by 1 July 2019 on how it will reduce amalgam use. The Commission will report by mid-2020 on the feasibility of phasing out dental amalgam preferably by 2030 to be accompanied by a legislative proposal, if appropriate. The action is part of a broader package to ratify and implement the Minamata Convention on Mercury.

“The children of Europe have won. The next generation in Europe will be safe from mercury dental fillings.”

said Charlie Brown, President of the World Alliance for Mercury-Free Dentistry.

“With this agreement Europe takes an important step towards returning to world leadership in implementing the Minamata Convention. These steps towards a phase out of dental amalgam will now resonate across the world.”

said Elena Lymberidi-Settimo of the European Environment Bureau.

“Amalgam is a primitive polluting device. It is technically inferior to today’s modern alternatives. Dentistry’s amalgam era is over, a fact embraced enthusiastically by thousands of European dentists and accepted by the others.”

said U.K. dentist Graeme Munro-Hall, chair of the Transition and Training task force of the World Alliance for Mercury-Free Dentistry.

“We welcome this agreement with mixed feelings. Such a decision should not only lead to a reduction of mercury in the EU, but it is also an open acknowledgement that mercury fillings should not have a place in our society. We regret that the measures for a full phase out of dental amalgam proposed by Stefan Eck (Rapporteur), did not survive the trilogue discussion. It is a missed opportunity to actually reduce the largest presence of mercury in the EU at its very source: dental amalgam.”

said Philippe Vandendaele of Health Care Without Harm Europe.

“This partial ban on dental amalgams is excellent news, especially for children’s health. It will not only help protect the health of mothers and children but also contribute to reducing everyone’s environmental exposure to mercury. Several Member States either disallow amalgam use or have already reduced it to less than 10% of all dental fillings. We hope each Member States will now take seriously its duty to reduce amalgam use for everyone.”

said Genon Jensen of Health and Environmental Alliance.

More Information

The Burden of Endocrine Disruptors

Endocrine disrupting chemicals and reproductive health, by “Bonhomme”

Around a hundred scientists asked Europe and the international community to act against endocrine disrupting chemicals. They condemned the use of strategies for manufacturing doubt employed by industries in the climate change battle.

  • Image sources: Let’s stop the manipulation of science, Le Monde, 29.11.2016.
The Investigation
  1. The Manufacture of a Lie.
  2. A Denial of the State of the Science.
  3. The Interference of the United States.
  4. The Discreet but Major Gift to the Pesticides Lobby.
Endocrine Disruptors

Phthalates found in all urine samples of pregnant women tested in France

Bisphenol A was found in more than 70% of women tested

France’s biggest biomonitoring study has revealed traces of at least one endocrine disruptor in almost all 4,000 pregnant women surveyed.

The organic pollutants included in the study were bisphenol A, phthalates, pyrethroids (insecticides), dioxins, furans, PCBs, flame retardants and perfluorinated compounds.

Bisphenol A was found in more than 70% of women tested and almost all samples – 99.6% – had traces of phthalates. Samples from 208 women tested positive for at least one of the following substances: dioxins, furans and polychlorinated biphenyls (PCBs). All three substances, all of which are now banned, persist for a long time in the environment.

EDCs found in almost all urine samples of pregnant women tested in France, Health and Environment Alliance, December 2016.

The principle source of exposure cited in the study is through food consumption. Other routes of high exposure include indoor and outdoor air.

The results were at a slightly lower level than in previous studies. Decreases may be partly explained by the introduction of regulations (atrazine, dioxins, furans) and reduced use due to industrial developments (bisphenol A, certain phthalates and organophosphate pesticides).

The results of the current study will be supplemented with findings on metal contaminants. A third phase will provide public health decision makers with recommendations on pyrethroids (being used as substitutes for organophosphate pesticides) and PCBs.

Allergy Exposure During Pregnancy Changes the Brain Make-Up of Offspring

Discovery could help explain links between maternal allergies and ADHD, autism

“This is evidence that prenatal exposure to allergens alters brain development and function and that could be an underappreciated factor in the development of neurodevelopmental disorders,”

said Kathryn Lenz, an Ohio State assistant professor of psychology.

A new study in rats could begin to explain why allergies during pregnancy are linked to higher risks for attention-deficit hyperactivity disorder and autism in children.

Researchers at The Ohio State University found significant changes in the brain makeup of fetuses and newborn rats exposed to allergens during pregnancy.

“We’re really interested in figuring out unknown factors in psychological disorders and in differences between male and female brain development as it relates to autism, ADHD and other disorders,”

Lenz said.

Animals that lived to adulthood after allergen exposure before birth showed signs of hyperactivity and antisocial behavior and decreased anxiety.

Though there are established links between allergies and ADHD and autism – as well as between inflammation and risk of autism, schizophrenia and ADHD – the cellular-level changes that could contribute to those connections largely remain a mystery.

Read Allergies during pregnancy contribute to changes in the brains of rat offspring, The Ohio State University, November 16, 2016.

Could a pap smear done early in pregnancy help doctors diagnose babies with genetic diseases?

Fetal genome profiling at 5 weeks of gestation after noninvasive isolation of trophoblast cells from the endocervical canal

Noninvasive peek at fetal DNA

Single-gene mutations are responsible for a large number of diseases and contribute to a sizeable fraction of pediatric hospitalizations and deaths. Current methods for prenatal diagnosis of such mutations are limited because they are invasive (except for detection of circulating fetal DNA, which is safe but can be difficult to perform accurately) and most cannot be performed early in pregnancy.

Pap Smear Early in Pregnancy Could Reveal Genetic Disorders Earlier, livescience, November 2, 2016.

Jain et al. now demonstrate a way to isolate and analyze trophoblast cells, which carry fetal DNA, by noninvasively obtained Papanicolaou smears. The authors show that analysis of the DNA in these cells presents an accurate reflection of the fetal genotype as early as 5 weeks of gestation, without the risk posed by invasive procedures.


Fetal genome profiling at 5 weeks of gestation after noninvasive isolation of trophoblast cells from the endocervical canal, sciencemag, 02 Nov 2016.

Single-gene mutations account for more than 6000 diseases, 10% of all pediatric hospital admissions, and 20% of infant deaths. Down syndrome and other aneuploidies occur in more than 0.2% of births worldwide and are on the rise because of advanced reproductive age. Birth defects of genetic origin can be diagnosed in utero after invasive extraction of fetal tissues. Noninvasive testing with circulating cell-free fetal DNA is limited by a low fetal DNA fraction. Both modalities are unavailable until the end of the first trimester. We have isolated intact trophoblast cells from Papanicolaou smears collected noninvasively at 5 to 19 weeks of gestation for next-generation sequencing of fetal DNA. Consecutive matched maternal, placental, and fetal samples (n = 20) were profiled by multiplex targeted DNA sequencing of 59 short tandem repeat and 94 single-nucleotide variant sites across all 24 chromosomes. The data revealed fetal DNA fractions of 85 to 99.9%, with 100% correct fetal haplotyping. This noninvasive platform has the potential to provide comprehensive fetal genomic profiling as early as 5 weeks of gestation.