Early-life factors and endometriosis risk

Insight into the Potential Mechanisms of Endocrine Disruption by Dietary Phytoestrogens in the Context of the Etiopathogenesis of Endometriosis

Phytoestrogens (PEs) are estrogen-like nonsteroidal compounds derived from plants (e.g., nuts, seeds, fruits, and vegetables) and fungi that are structurally similar to 17β-estradiol. PEs bind to all types of estrogen receptors, including ERα and ERβ receptors, nuclear receptors, and a membrane-bound estrogen receptor known as the G protein-coupled estrogen receptor (GPER). As endocrine-disrupting chemicals (EDCs) with pro- or antiestrogenic properties, PEs can potentially disrupt the hormonal regulation of homeostasis, resulting in developmental and reproductive abnormalities. However, a lack of PEs in the diet does not result in the development of deficiency symptoms. To properly assess the benefits and risks associated with the use of a PE-rich diet, it is necessary to distinguish between endocrine disruption (endocrine-mediated adverse effects) and nonspecific effects on the endocrine system. Endometriosis is an estrogen-dependent disease of unknown etiopathogenesis, in which tissue similar to the lining of the uterus (the endometrium) grows outside of the uterus with subsequent complications being manifested as a result of local inflammatory reactions. Endometriosis affects 10-15% of women of reproductive age and is associated with chronic pelvic pain, dysmenorrhea, dyspareunia, and infertility. In this review, the endocrine-disruptive actions of PEs are reviewed in the context of endometriosis to determine whether a PE-rich diet has a positive or negative effect on the risk and course of endometriosis.

The relationship between endometriosis and diet

Endometriosis is an oestrogen dependent, benign, chronic inflammatory disease characterised by ectopic endometrial implants. Current medical practices for the treatment of the disease are associated with several side effects over long periods, making the effect of diet on endometriosis an important aspect. To alleviate this need, we review related literature to identify the association between nutrients and endometriosis and to find the probable therapeutic effects of the nutrients and foods on endometriosis. Despite variations among the findings, several of the prior studies point to an inverse relationship between endometriosis and the consumption of fruits, vegetables, dairy products, and omega-3 fatty acids. Another common finding among the studies is the increased risk of endometriosis with higher consumption of trans-unsaturated fatty acids and red meat. Due to the limited size of the samples in existing literature, however, significance of the association between diet and endometriosis is not conclusive. Further research is needed to better identify the role of diet on endometriosis.

Oestrogens and progesterone in human milk and their effects on infant health outcomes: A narrative review

Human milk (HM) is a complex biological system that contains a wide range of bioactive components including oestrogens and progesterone. Whilst maternal oestrogens and progesterone concentrations drop rapidly after birth, they remain detectable in HM across lactation. Phytoestrogens and mycoestrogens, which are produced by plants and fungi, are also present in HM and can interact with oestrogen receptors to interfere with normal hormone functions. Despite the potential impact of HM oestrogens and progesterone on the infant, limited research has addressed their impact on the growth and health of breastfed infants. Furthermore, it is important to comprehensively understand the factors that contribute to these hormone levels in HM, in order to establish effective intervention strategies. In this review, we have summarized the concentrations of naturally occurring oestrogens and progesterone in HM from both endogenous and exogenous sources and discussed both maternal factors impacting HM levels and relationships with infant growth.

Epigenetics, endometriosis and sex steroid receptors: An update on the epigenetic regulatory mechanisms of estrogen and progesterone receptors in patients with endometriosis

Endometriosis is a benign gynecological disease affecting ∼10% of reproductive-aged women and is defined as the presence of endometrial glands and stroma outside the uterine cavity. Endometriosis can cause a variety of health problems, from pelvic discomfort to catamenial pneumothorax, but it's mainly linked with severe and chronic pelvic pain, dysmenorrhea, and deep dyspareunia, as well as reproductive issues. The pathogenesis of endometriosis involves an endocrine dysfunction, with estrogen dependency and progesterone resistance, and inflammatory mechanism activation, together with impaired cell proliferation and neuroangiogenesis. The present chapter aims to discuss the main epigenetic mechanisms related to estrogen receptors (ERs) and progesterone receptors (PRs) in patients with endometriosis. There are numerous epigenetic mechanisms participating in endometriosis, regulating the expression of the genes encoding these receptors both indirectly, through the regulation of transcription factors, and directly, through DNA methylation, histone modifications, micro RNAs and long noncoding RNAs. This represents an open field of investigation, which may lead to important clinical implications such as the development of epigenetic drugs for the treatment of endometriosis and the identification of specific and early biomarkers for the disease.

Birth Outcomes in DES Children and Grandchildren: A Multigenerational National Cohort Study on Informative Families

OBJECTIVE

Diethylstilbestrol (DES), a potent synthetic nonsteroidal estrogen belonging to the family of endocrine disrupting chemicals (EDCs), can cross the placenta and may cause permanent adverse health effects in the exposed mothers, their children (exposed in utero), and also their grandchildren through germline contribution to the zygote. This study evaluated pregnancy duration and birthweight (BW) variations in the children and grandchildren born before, during, and after maternal DES treatment in the same informative families, to rule out genetic, endocrine, and environmental factors.

DESIGN AND SETTING

Nationwide retrospective observational study on 529 families of DES-treated women registered at the HHORAGES-France Association. The inclusion criteria were: (i) women with at least three pregnancies and three viable children among whom the first was not exposed in utero to DES, followed by one or more children with fetal exposure to DES, and then by one or more children born after DES treatment; (ii) women with at least one pre-DES or post-DES grandchild and one DES grandchild; (iii) confirmed data on total DES dose. Women with severe pathologies or whose illness status, habitat, lifestyle habits, profession, treatment changed between pregnancies, and all mothers who reported pregnancy-related problems, were excluded.

RESULTS

In all, 74 women met all criteria. The preterm birth (PTB) rate was 2.7% in pre-DES, 14.9% in DES, and 10.8% in post-DES children (Cochran-Armitage test for trend, p = 0.0095). The mean BW was higher in DES than pre-DES full-term neonates (≥37 weeks of gestation) (p = 0.007). In grandchildren, BW was not different, whereas the PTB and low BW rates were slightly increased in children of DES women.

CONCLUSIONS

These data within the same informative families show the DES impact on BW and PTB in DES and post-DES children and grandchildren. In particular, mean BW was higher in DES than pre-DES full-term neonates. This result may be in opposition to previous data from American cohorts, which reported lower BW in DES children, but is consistent with animal study. Our retrospective observational study highlights a multigenerational and likely transgenerational effect of this EDC in humans.

Soy-Based Infant Formula Feeding and Uterine Fibroid Development in a Prospective Ultrasound Study of Black/African-American Women

BACKGROUND

Uterine fibroids are highly prevalent, benign tumors. They are the leading indication for hysterectomy, and Black women are disproportionally burdened. Soy-based infant formula contains phytoestrogens, and exposure during sensitive developmental windows may adversely affect the developing uterus; early phytoestrogen treatment in rodent studies led to detrimental uterine effects, including increased fibroid risk in Eker rats. Limited epidemiological studies also have suggested increased fibroid development with soy formula infant feeding.

OBJECTIVE

The goal of this study was to examine the association between soy formula feeding in infancy and fibroid development in adulthood.

METHODS

We evaluated this association among 1,610 Black/African-American women age 23-35 y in the Study of Environment, Lifestyle & Fibroids (SELF). Soy formula feeding data was gathered directly from the participants' mothers (89%). A standardized ultrasound examination was conducted during 4 clinic visits over 5 y to detect fibroids ≥0.5cm in diameter. We used Cox proportional hazards regression to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) for the association between soy formula feeding and incident fibroids adjusted for early-life and adult factors. Fibroid growth was calculated as change in log-volume for fibroids matched at successive visits.

RESULTS

Of 1,121 fibroid-free participants at baseline, 150 (13%) were ever fed soy formula as infants, and 269 (24%) developed incident fibroids. We did not observe an association between ever being fed soy formula and incident fibroid risk (HR=1.08; 95% CI: 0.75, 1.54). However, participants fed soy formula within 2 months of birth and for >6 months (n=53) had an elevated risk of fibroid incidence in comparison with those never fed soy formula (HR=1.56; 95% CI: 0.92, 2.65). Fibroid growth rates did not differ.

DISCUSSION

Adding support to limited human data, this prospective fibroid study found that soy-based formula feeding during infancy was associated with a suggestive increase in risk of ultrasound-identified incident fibroids in adulthood. https://doi.org/10.1289/EHP11089.

Endometriosis and environmental factors: a critical review

This review provides an overview of current knowledge on the relationship between various environmental factors and endometriosis. We successively searched for a given exposure factor combined with the word "endometriosis." The literature was comprehensively analyzed and summarized by quoting only the most important and recent studies on each exposition factor. The data focused primarily on endocrine disruptors, such as dioxins and polychlorinated biphenyls, that appear to have the strongest effect. Intriguing data suggest a link with night work, sun exposure and red meat consumption. For the other risk factors studied, particularly those related to lifestyle (tobacco consumption, alcohol, coffee, soy, physical exercise), the data are not sufficient to draw conclusions. In summary, the epidemiological evidence does not support a strong, scientific link between exposure to environmental factors and endometriosis. The complexity of this disease requires advanced study designs and standardized methodology. Future studies should be carefully designed to address these issues to advance our understanding of the impact of the environment and its consequences on endometriosis.

The Potential Relationship Between Environmental Endocrine Disruptor Exposure and the Development of Endometriosis and Adenomyosis

Women with endometriosis, the growth of endometrial glands and stroma outside the uterus, commonly also exhibit adenomyosis, the growth of endometrial tissues within the uterine muscle. Each disease is associated with functional alterations in the eutopic endometrium frequently leading to pain, reduced fertility, and an increased risk of adverse pregnancy outcomes. Although the precise etiology of either disease is poorly understood, evidence suggests that the presence of endometriosis may be a contributing factor to the subsequent development of adenomyosis as a consequence of an altered, systemic inflammatory response. Herein, we will discuss the potential role of exposure to environmental toxicants with endocrine disrupting capabilities in the pathogenesis of both endometriosis and adenomyosis. Numerous epidemiology and experimental studies support a role for environmental endocrine disrupting chemicals (EDCs) in the development of endometriosis; however, only a few studies have examined the potential relationship between toxicant exposures and the risk of adenomyosis. Nevertheless, since women with endometriosis are also frequently found to have adenomyosis, discussion of EDC exposure and development of each of these diseases is relevant. We will discuss the potential mechanisms by which EDCs may act to promote the co-development of endometriosis and adenomyosis. Understanding the disease-promoting mechanisms of environmental toxicants related to endometriosis and adenomyosis is paramount to designing more effective treatment(s) and preventative strategies.

Developmental exposure to phytoestrogens found in soy: New findings and clinical implications

Exposure to naturally derived estrogen receptor activators, such as the phytoestrogen genistein, can occur at physiologically relevant concentrations in the human diet. Soy-based infant formulas are of particular concern because infants consuming these products have serum genistein levels almost 20 times greater than those seen in vegetarian adults. Comparable exposures in animal studies have adverse physiologic effects. The timing of exposure is particularly concerning because infants undergo a steroid hormone-sensitive period termed "minipuberty" during which estrogenic chemical exposure may alter normal reproductive tissue patterning and function. The delay between genistein exposure and reproductive outcomes poses a unique challenge to collecting epidemiological data. In 2010, the U.S. National Toxicology Program monograph on the safety of the use of soy formula stated that the use of soy-based infant formula posed minimal concern and emphasized a lack of data from human subjects. Since then, several new human and animal studies have advanced our epidemiological and mechanistic understanding of the risks and benefits of phytoestrogen exposure. Here we aim to identify clinically relevant findings regarding phytoestrogen exposure and female reproductive outcomes from the past 10 years, with a focus on the phytoestrogen genistein, and explore the implications of these findings for soy infant formula recommendations. Research presented in this review will inform clinical practice and dietary recommendations for infants based on evidence from both clinical epidemiology and basic research advances in endocrinology and developmental biology from mechanistic in vitro and animal studies.

Multigenerational endometriosis : consequence of fetal exposure to diethylstilbestrol ?

BACKGROUND

Endometriosis, which affects 10-15 % of women of reproductive age, is an estrogen-driven condition influenced by environmental and genetic factors. Exposition to estrogen-like endocrine-disrupting chemicals (EDCs) has been reported to contribute to the fetal origin of this disease.

CASE PRESENTATION

We report here an informative family in which all prenatally DES-exposed daughters and subsequent granddaughters presented endometriosis, whereas the unexposed first daughter and her progeny presented no gynecological disorders. Moreover, the only post-pubertal great-granddaughter, who presents chronic dysmenorrhea that remains resistant to conventional therapy, is at risk of developing endometriosis. The mother (I-2) was prescribed DES (30 mg/day for 3 months) to inhibit lactation after each delivery.

CONCLUSIONS

Although a direct causal link between the grandmother's treatment with DES and the development of endometriosis in possibly three exposed generations remains speculative, this report strengthens the suspicion that fetal exposition to DES contributes to the pathogenesis of adult diseases, such as endometriosis. It also highlights a multigenerational and likely transgenerational effect of EDCs.

Current Perspectives on the Beneficial Effects of Soybean Isoflavones and Their Metabolites for Humans

Soybeans are rich in proteins and lipids and have become a staple part of the human diet. Besides their nutritional excellence, they have also been shown to contain various functional components, including isoflavones, and have consequently received increasing attention as a functional food item. Isoflavones are structurally similar to 17-β-estradiol and bind to estrogen receptors (ERα and ERβ). The estrogenic activity of isoflavones ranges from a hundredth to a thousandth of that of estrogen itself. Isoflavones play a role in regulating the effects of estrogen in the human body, depending on the situation. Thus, when estrogen is insufficient, isoflavones perform the functions of estrogen, and when estrogen is excessive, isoflavones block the estrogen receptors to which estrogen binds, thus acting as an estrogen antagonist. In particular, estrogen antagonistic activity is important in the breast, endometrium, and prostate, and such antagonistic activity suppresses cancer occurrence. Genistein, an isoflavone, has cancer-suppressing effects on estrogen receptor-positive (ER+) cancers, including breast cancer. It suppresses the function of enzymes such as tyrosine protein kinase, mitogen-activated kinase, and DNA polymerase II, thus inhibiting cell proliferation and inducing apoptosis. Genistein is the most biologically active and potent isoflavone candidate for cancer prevention. Furthermore, among the various physiological functions of isoflavones, they are best known for their antioxidant activities. S-Equol, a metabolite of genistein and daidzein, has strong antioxidative effects; however, the ability to metabolize daidzein into S-equol varies based on racial and individual differences. The antioxidant activity of isoflavones may be effective in preventing dementia by inhibiting the phosphorylation of Alzheimer's-related tau proteins. Genistein also reduces allergic responses by limiting the expression of mast cell IgE receptors, which are involved in allergic responses. In addition, they have been known to prevent and treat various diseases, including cardiovascular diseases, metabolic syndromes, osteoporosis, diabetes, brain-related diseases, high blood pressure, hyperlipidemia, obesity, and inflammation. Further, it also has positive effects on menstrual irregularity in non-menopausal women and relieving menopausal symptoms in middle-aged women. Recently, soybean consumption has shown steep increasing trend in Western countries where the intake was previously only 1/20-1/50 of that in Asian countries. In this review, I have dealt with the latest research trends that have shown substantial interest in the biological efficacy of isoflavones in humans and plants, and their related mechanisms.

Clinical factors influencing the pregnancy outcome after laparoscopic treatment in endometriosis-associated infertility patients: a retrospective study

INTRODUCTION

Endometriosis is an illness caused by the presence of foci of endometrial implants outside the uterine cavity. Laparoscopy (minimally invasive surgical method) is considered as the definitive treatment for Endometriosis.

METHOD

Clinical data from January 2014 till December 2018, between the ages of 20 and 40 years were collected. A total of 175 women with pelvic Endometriosis complicated with infertility, underwent laparoscopy in our hospital, were followed up to assess fertility outcome. We analyzed using univariate logistic regression analysis as well as multivariate logistic analysis.

RESULTS

We analyzed the relationship between them by logistic regression analysis. Univariate logistic regression analysis indicated that the significant factors for influencing pregnancy were the following factors: age, infertility types: primary or secondary infertility, treatment with Gonadotrophin Releasing Hormone-agonist, r-AFS grade, operative method: excision or ablation. And multivariate logistic regression using all the factors also revealed that age, infertility types: primary or secondary, treatment with GnRH-a, revised- American Fertility Society grading and operative method: excision or ablation were positively correlated and were the significant factors to influence pregnancy outcome. While the other factors such as Body Mass Index, and endometriosis along with other gynecological pathology were not statistically significant.

CONCLUSIONS

In this study, we found out that age, infertility type, treatment with Laparoscopy surgery, use of GnRH-a after the operation, grading of the disease, and different types of operative methods were found to be significant and were found to be the factors which influenced the pregnancy outcome.

Neither soyfoods nor isoflavones warrant classification as endocrine disruptors: a technical review of the observational and clinical data

Soybeans are a rich source of isoflavones, which are classified as phytoestrogens. Despite numerous proposed benefits, isoflavones are often classified as endocrine disruptors, based primarily on animal studies. However, there are ample human data regarding the health effects of isoflavones. We conducted a technical review, systematically searching Medline, EMBASE, and the Cochrane Library (from inception through January 2021). We included clinical studies, observational studies, and systematic reviews and meta-analyses (SRMA) that examined the relationship between soy and/or isoflavone intake and endocrine-related endpoints. 417 reports (229 observational studies, 157 clinical studies and 32 SRMAs) met our eligibility criteria. The available evidence indicates that isoflavone intake does not adversely affect thyroid function. Adverse effects are also not seen on breast or endometrial tissue or estrogen levels in women, or testosterone or estrogen levels, or sperm or semen parameters in men. Although menstrual cycle length may be slightly increased, ovulation is not prevented. Limited insight could be gained about possible impacts of in utero isoflavone exposure, but the existing data are reassuring. Adverse effects of isoflavone intake were not identified in children, but limited research has been conducted. After extensive review, the evidence does not support classifying isoflavones as endocrine disruptors.

Effects of Environmental Endocrine-Disrupting Chemicals on Female Reproductive Health

Environmental endocrine-disrupting chemicals (EDCs) are xenobiotic compounds that are frequently contacted in daily life. With the species and quantity of substances created and utilized by human beings significantly surpassing the self-purification capacity of nature, a large number of hazardous substances are enriched in the human body through the respiratory tract, digestive tract, and skin. Some of these compounds cause many problems endangering female reproductive health by simulating/antagonizing endogenous hormones or affecting the synthesis, metabolism, and bioavailability of endogenous hormones, including reproductive disorders, fetal birth defects, fetal developmental abnormalities, endocrine and metabolic disorders, and even gynecological malignancies. Therefore, the study of the relationship between environmental EDCs and female reproductive diseases and related mechanisms is of considerable significance to women, children health care, and improve the quality of the population.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

Early life factors for endometriosis: a systematic review

BACKGROUND

Despite its high prevalence and health burden, many aspects of endometriosis remain unclear, including risk factors and the underlying biological mechanisms. Exposures during early life, including in utero, are thought to play an important role in the subsequent onset of the condition. To date, however, much of the evidence from studies on early life exposures and diagnosed endometriosis appears mixed and difficult to assess.

OBJECTIVE AND RATIONALE

This study aims to provide a systematic review of the epidemiologic evidence on early life factors associated with the subsequent diagnosis of endometriosis. In utero and early life exposures have previously been linked to a range of adult health outcomes, including infertility.

SEARCH METHODS

A systematic review of case-control, cross-sectional and cohort studies was conducted using the search terms 'endometriosis'[MeSH] AND ('risk factors'[MeSH] OR 'protective factors'[MeSH]) AND ('in utero', 'fetal', 'neonatal, 'perinatal', 'developmental origins', 'early life', 'childhood' OR 'life course') in Embase, PubMed and Scopus databases. The review included articles published in English until 10 June 2018 with original data from studies with diagnosed endometriosis. The quality of primary studies was evaluated using the Newcastle-Ottawa Scale by both authors independently. Due to the degree of inconsistency in the measurements and study methods, a qualitative assessment of findings was undertaken rather than meta-analysis.

OUTCOMES

The search retrieved 70 records without duplicates that contained 20 records on human case-control, cross-sectional or cohort studies, from which 11 papers/studies were selected based on their assessment score. The majority of studies found that women born with low birthweight (<2.5 kg or <5.5 lb) were more likely to be diagnosed with endometriosis. For other early life factors, the evidence is mixed or limited, with further research needed on the association of endometriosis with preterm birth, in utero exposure to diethylstilbestrol and to maternal smoking, passive smoking in early life, and infant formula feeding (compared with breastfeeding).

WIDER IMPLICATIONS

While the weight of evidence points to low birthweight as a risk factor for diagnosis of endometriosis, future research is warranted on this and other key early life exposures where the findings are mixed to provide more robust evidence and for insights on potential causal pathways. Such research, however, needs to address current methodological issues, such as the use of prospective data from large population-based studies, better diagnostic methods to confirm disease free status, more consistent definitions of variables and consideration of potential biological mechanisms to guide the analyses. The improvements will advance the future synthesis of evidence to support clinically relevant risk assessment for a more timely diagnosis and treatment of endometriosis.

Environmental risk factors for endometriosis: A critical evaluation of studies and recommendations from the epidemiologic perspective

Purpose of review

Recent studies of environmental chemicals and endometriosis were critically evaluated from the epidemiologic perspective to identify aspects of study design and analyses that may contribute to discrepant results across studies.

Recent findings

Of the 29 studies reviewed, 12 studies used new approaches to population-based sampling. The remaining studies were conducted primarily among patients undergoing pelvic surgery; controls may not represent the exposure experience of the underlying study base, resulting in biased estimates of associations. Most studies used biologic specimens collected near diagnosis and varied in analytic approaches to minimize bias. Few studies investigated ovarian, deep-infiltrating, and peritoneal endometriosis presentations separately.

Summary

Recommendations to move the field forward include: (1) control selection from a defined study base, (2) exposure characterization during the etiologically-relevant window, (3) employment of best practices to minimize bias in analyses, and (4) separate consideration of endometriosis presentations that may be etiologically-distinct entities.

In utero and early life exposures in relation to endometriosis in adolescents and young adults

OBJECTIVE

Endometriosis is a common gynecologic disorder often associated with severe pelvic pain and infertility with few known modifiable risk factors. We investigated whether in utero and early life exposures are associated with surgically diagnosed endometriosis among adolescents and young adults.

STUDY DESIGN

This case-control study, including 295 laparoscopically-confirmed endometriosis cases and 309 population-based controls aged <25 years, was conducted using data from The Women's Health Study: From Adolescence to Adulthood which enrolled participants from 2012 to 2018. Information on in utero and early life factors were collected using a modified WERF EPHect questionnaire at enrollment, including their mother's age at delivery, birthweight, gestation length, exposure to smoking in utero and secondhand smoke during childhood up to age 13, and if the participant was breastfed.

RESULTS

Median age at enrollment was 17 years (range 12-24) in cases and 22 years (range 7-24) in controls, with 83 % and 68 % non-Hispanic whites, respectively. The majority of cases (95 %) were rASRM stage I or II at diagnostic surgery. Exposure to breastfeeding in early life was associated with lower odds of endometriosis diagnosis (OR = 0.39, 95 % CI = 0.21-0.74). Exposure to secondhand smoke during childhood due to maternal smoking was associated with increased odds of endometriosis diagnosis (OR = 2.70, 95 % CI = 1.11-6.60).

CONCLUSIONS

Among adolescents and young adults, our data suggest exposures to breastfeeding in early life and secondhand smoke during childhood may be associated with endometriosis risk, providing insight into etiologic pathways to be explored in this young population.

Early maternal separation accelerates the progression of endometriosis in adult mice

BACKGROUND

A large body of research highlights the importance of early-life environmental impact on the health outcome in adulthood. However, whether early-life adversity (ELA) has any impact on the development of endometriosis is completely unclear. In this study, we tested the hypothesis that ELA, as manifested by neonatal separation, can accelerate the progression of endometriosis in mouse through activation of the adrenergic receptor β2 (ADRB2) signaling pathway, leading to increased angiogenesis and progression of endometriotic lesions.

METHODS

Eight female Balb/C mice, in late pregnancy, were used used for this study, which later gave birth to 22 female newborn pubs. Eleven additional female Balb/C mice were also used as donors of uterine tissues. The 22 newborn pubs were randomly divided into 2 equal-sized groups, maternal separation (MS) and no separation (NS). Pubs in the MS group were separated from their dams for 3 h/day from postnatal day (PND) 1 to 21, while those in the NS control remained in the home cage with their dams. In adulthood (8-week old), 3 mice in each group were randomly selected to undergo a battery of behavior tests. The remaining 8 mice in each group were induced with endometriosis by intraperitoneal injection of uterine fragments from donor mice. Four weeks after the induction, all mice were sacrificed and their endometriotic lesions were excised for quantification and then prepared for immunohistochemistry analysis.

RESULTS

We confirmed that MS during infancy resulted in anxiety and depression-like behaviors as previously reported. We also found that in MS mice the lesion weight was increased by over 2 folds and generalized hyperalgesia was also significantly increased as compared with NS mice. Immunostaining analysis demonstrated that MS accelerated the development of endometriosis likely through decreased dopamine receptor D2 (DRD2) expression and activation of the ADRB2/cAMP-response element binding protein (CREB) signaling pathway, leading to increased angiogenesis and progression of endometriotic lesions.

CONCLUSIONS

Exposure of female mouse pups to ELA such as MS during their infancy period accelerates the progression of endometriosis, possibly through altered neuronal wiring and hyperactivity of the hypothalamic-pituitary-adrenal axis.

Early-life factors, in-utero exposures and endometriosis risk: a meta-analysis

This meta-analysis aimed to offer a general picture of the available data on the effects of early-life factors on the risk of developing endometriosis in adult life. An advanced, systematic search of the online medical databases PubMed, EMBASE and CINAHL was limited to full-length manuscripts published in English in peer-reviewed journals up to February 2019. Log of relative risk (RR) was employed to calculate the pooled effect sizes using both fixed and random effects modelling and I-squared tests to assess heterogeneity. Funnel plots were used to investigation publication bias. The meta-analysis was registered in PROSPERO (ID CRD42019138668). Six studies that included a total of 2360 women affected by endometriosis were analysed. The pooled results showed that the risk of developing endometriosis in adult life was significantly increased by being born prematurely (logRR 0.21, 95% CI -0.03 to 0.40), having a low birthweight (logRR 0.35, 95% CI -0.15 to 0.54), being formula-fed (logRR 0.65, 95% CI -0.35 to 0.95) and having been exposed to diethylstilbestrol (DES) in utero (logRR 0.65, 95% CI 0.26 to 1.04. Among intrauterine and early neonatal exposures, prematurity, birthweight, formula feeding and DES were risk factors for the development of endometriosis in adult life.

Associations of perinatal characteristics with endometriosis: a nationwide birth cohort study

BACKGROUND

Perinatal characteristics are associated with subsequent risk of several chronic diseases. Previous studies regarding endometriosis were based on small samples and retrospective data and were limited by unmeasured confounding bias, leading to conflicting and inconclusive findings. We investigated the associations of maternal and birth characteristics with risk of endometriosis among Swedish women of reproductive age.

METHODS

This total-population register-based cohort study consisted of 628 312 singleton women born in Sweden between 1973 and 1987, who were followed for diagnosed endometriosis from age 15 years until the end of 2012. Multivariable Cox regression was applied to examine associations with perinatal characteristics. Residual unmeasured confounding was assessed through within-family and E-value analyses.

RESULTS

During follow-up, 8262 women received an endometriosis diagnosis. There were clear dose-response/linear associations of endometriosis with lower maternal education, endometriosis in the mother [adjusted hazard ratio (aHR): 2.24, 95% confidence interval (CI): 2.04-2.46], maternal smoking during pregnancy (aHR: 1.18, 95% CI: 1.04-1.33 for moderate smoker and aHR: 1.36, 95% CI: 1.18-1.57 for heavy smoker vs non-smoker), lower birthweight, and lower birthweight-for-gestational age (aHR: 0.93 per standard deviation increase, 95% CI: 0.91-0.95). Within-family and E-value analyses suggested that these perinatal characteristics are robust predictors of the incidence of endometriosis. We also found that an estimated 26% of the association between maternal smoking and early-onset endometriosis could be explained by birthweight-for-gestational age.

CONCLUSION

This study finds support for fetal origins of endometriosis, in that exposure to adverse environment or restricted development during the perinatal period may increase the risk. Further research is needed to provide an understanding of the underlying mechanisms.

Infant Formula Feeding Changes the Proliferative Status in Piglet Neonatal Mammary Glands Independently of Estrogen Signaling

BACKGROUND

Soy infant formula contains isoflavones, which are able to bind to and activate estrogen receptor (ER) pathways. The mammary gland is sensitive to estrogens, raising concern that the use of soy formulas may promote premature development.

OBJECTIVE

We aimed to determine if soy formula feeding increases mammary gland proliferation and differentiation in comparison to other infant postnatal diets.

METHODS

White-Dutch Landrace piglets aged 2 d received either sow milk (Sow), or were provided milk formula (Milk), soy formula (Soy), milk formula supplemented with 17-beta-estradiol (2 mg/(kg·d); M + E2), or milk formula supplemented with genistein (84 mg/L of diet; M + G) until day 21. Mammary gland proliferation and differentiation was assessed by histology, and real-time RT-PCR confirmation of differentially expressed genes identified by microarray analysis.

RESULTS

Mammary terminal end bud numbers were 19-31% greater in the Milk, Soy, and M + G groups relative to the Sow and M + E2, P <0.05. Microarray analysis identified differentially expressed genes between each formula-fed group relative to the Sow (±1.7-fold, P <0.05). Real-time RT-PCR confirmed 2- to 4-fold increases in mRNA transcripts of genes involved in cell proliferation, insulin-like growth factor 1 (IGF1), fibroblast growth factor 10 (FGF10), and fibroblast growth factor 18 (FGF18), in all groups relative to the Sow, P <0.05. In contrast, genes involved in cell differentiation and ductal morphogenesis, angiotensin II receptor type 2 (AGTR2), microtubule associated protein 1b (MAP1B), and kinesin family member 26b (KIF26B), were significantly upregulated by 2-, 4-, and 13-fold, respectively, in the M + E2 group. Additionally, mRNA expression of ER-specific gene targets, progesterone receptor (PGR), was increased by 12-fold, and amphiregulin (AREG) and Ras-like estrogen regulated growth inhibitor (RERG) expression by 1.5-fold in the M + E2 group, P <0.05. In the soy and M + G groups, mRNA expressions of fatty acid synthesis genes were increased 2- to 4-fold.

CONCLUSIONS

Our data indicate soy formula feeding does not promote ER-signaling in the piglet mammary gland. Infant formula feeding (milk- or soy-based) may initiate proliferative pathways independently of estrogenic signaling.

Smoke, alcohol and drug addiction and female fertility

BACKGROUND

Considerable interest has been gathered on the relevant impact of preventable factors, including incorrect lifestyle and unhealthy habits, on female fertility. Smoking, alcohol and addictive drugs consumption represent a major concern, given the broad range of diseases which might be favored or exacerbated by these dependable attitudes. Despite the well-characterized effects of prenatal exposure on pregnancy outcomes and fetus health, a substantial proportion of women of reproductive age is still concerned with these habits. At present, the impact of smoke, alcohol and addictive drugs on women fertility, and, particularly, the specific targets and underlying mechanisms, are still poorly understood or debated, mainly due to the scarcity of well-designed studies, and to numerous biases.

OBJECTIVE

The current review will provide a comprehensive overview of clinical and experimental studies in humans and animals addressing the impact of smoke, alcohol and addictive drugs on female fertility, by also embracing effects on ovary, oviduct, and uterus, with particular reference to primary endpoints such as ovarian reserve, steroidogenesis, ovulation and menstrual cycle, oviduct function and uterus receptivity and implantation. A brief focus on polycystic ovary syndrome and endometriosis will be also included.

METHODS

A Pubmed literature search was performed with selected keywords; articles were individually retrieved by each author. No limitation was set for publication date. Articles in languages other than English were excluded. Additional articles were retrieved from references list of selected manuscripts.

RESULTS AND CONCLUSIONS

Currently, the most consistent evidences of a detrimental effect of smoke, alcohol and addictive drugs on specific domains of the female reproductive function are provided by experimental studies in animals. Overall, clinical studies suggest that smoking is associated to decreased fertility, although causal inference should be further demonstrated. Studies addressing the effect of alcohol consumption on female fertility provide conflicting results, although the majority reported lack of a correlation. Extremely scarce studies investigated the effects of addictive drugs on female fertility, and the specific actions of selected drugs have been difficult to address, due to multidrug consumption.

Birth weight, childhood body mass index and height and risks of endometriosis and adenomyosis

Background: Body size in adult life is likely associated with risks of endometriosis and adenomyosis, yet little is known about associations with body size earlier in life.Aim: To examine whether birth weight, childhood body mass index (BMI) and height are associated with risks of endometriosis and adenomyosis.Subjects and methods: From the Copenhagen School Health Records Register, 171,447 girls born 1930-1996, with measured weights and heights at ages 7-13 were included. Outcomes were obtained from health registers. Cox regressions were performed to estimate hazard ratios (HR) and 95% confidence intervals (CI).Results: During follow-up, 2149 endometriosis cases and 1410 adenomyosis cases were diagnosed. Childhood BMI was inversely associated with endometriosis (HR = 0.92 [95% CI: 0.88-0.96] per z-score at age 7). In contrast, childhood height was positively associated with endometriosis (HR = 1.09 [95% CI: 1.05-1.14] per z-score at age 7). Associations with childhood body size did not differ by endometriosis location. Childhood BMI and height had limited associations with adenomyosis. Birth weight was not associated with endometriosis or adenomyosis.Conclusion: Lean and tall girls are more often diagnosed with endometriosis, but not adenomyosis. These findings suggest that indicators of endometriosis risk are already apparent at early ages.

Is Stress a Cause or a Consequence of Endometriosis?

Clinical studies clearly indicate that endometriosis is a condition associated with high levels of chronic stress. The stress intensity correlates with pain severity and disease extension. However, it is unknown whether chronic stress represents a primary cause of endometriosis and, therefore, if avoiding or treating chronic stress may reduce the risk of developing endometriosis. Repeated, uncontrolled stress either before or after experimental endometriosis induction promotes disease mechanisms and accelerates lesion growth in rodents. Furthermore, patients with endometriosis have a heightened risk of other inflammatory and immune-related diseases, many of which have also been associated with stress. Here, we review the latest evidences regarding the relationship between chronic stress and endometriosis and discuss the potential bidirectional aspect of such association. Further research may clarify if endometriosis is a cause and/or a consequence of stress and whether stress-reducing therapies are effective to mitigate symptoms and slow down the development of endometriotic lesions.

Environmental Endocrine Disruptors and Endometriosis

As a consequence of industrialization, thousands of man-made chemicals have been developed with few undergoing rigorous safety assessment prior to commercial use. Ubiquitous exposure to these compounds, many of which act as endocrine-disrupting chemicals (EDCs), has been suggested to be one factor in the increasing incidence of numerous diseases, including endometriosis. Endometriosis, the presence of endometrial glands and stroma outside the uterus, is a common disorder of reproductive-age women. Although a number of population-based studies have suggested that exposure to environmental EDCs may affect a woman's risk of developing this disease, results of epidemiology assessments are often equivocal. The development of endometriosis is, however, a process occurring over time; thus, a single assessment of toxicant body burden cannot definitively be linked to causation of disease. For this reason, numerous investigators have utilized a variety of rodent models to examine the impact of specific EDCs on the development of experimental endometriosis. These studies identified multiple chemicals capable of influencing physiologic processes necessary for the establishment and/or survival of ectopic tissues in rodents, suggesting that these compounds may also be of concern for women. Importantly, these models serve as useful tools to explore strategies that may prevent adverse outcomes following EDC exposure.

Ovarian endometrioma - a possible finding in adolescent girls and young women: a mini-review

Young girls before menarche or menstruating adolescent women may experience long-term drug-resistant chronic pelvic pain, as well as other symptoms associated with pelvic mass. In such cases, it is of great importance to consider ovarian endometrioma in the differential diagnosis. In general, endometrioma is recognized as an ovarian cyst. However, in most cases, the pathology represents pseudocyst with a partial or complete endometrial-like lining with extraovarian adhesions and endometriotic implants which are likely to occur at the sites of ovarian adhesions and at the ceiling of the ovarian fossa. Ovarian endometriomas occur in 17–44% patients with endometriosis and account for 35% of all benign ovarian cysts. The time span from the onset of menarche to the time of endometrioma formation, which requires surgical intervention, has been evaluated to be a minimum of 4 years. The pathogenesis of early-life endometrioma may be different from other types of endometriosis. Diagnosis is often delayed, especially in adolescents, who tend to wait too long before seeking professional help. The three specific aims of treatment in adolescents with endometriosis and endometriomas are control of symptoms, prevention of further progression of the disease as well as preservation of fertility. Increasing evidence demonstrates association between ovarian endometriosis and ovarian cancer. In the present mini-review, we draw the particular attention of clinicians to such a possibility, even if relatively infrequently reported.

The Sex-Gender Effects in the Road to Tailored Botanicals

Phenols are a wide family of phytochemicals that are characterized by large chemical diversity and are considered to bioactive molecules of foods, beverages, and botanicals. Although they have a multitude of biological actions, their beneficial effects are rarely evidenced in clinical research with high scientific rigor. This may occur due to the presence of numerous confounders, such as the modulation of phenol bioavailability, which can be regulated by microbiota, age, sex-gender. Sex-gender is an important determinant of health and well-being, and has an impact on environmental and occupational risks, access to health care, disease prevalence, and treatment outcomes. In addition, xenobiotic responses may be strongly influenced by sex-gender. This review describes how sex–gender differentially influences the activities of phenols also in some critical periods of women life such as pregnancy and lactation, considering also the sex of fetuses and infants. Thus, sex–gender is a variable that must be carefully considered and should be used to propose directions for future research on the road to tailored medicine and nutrition.

Soy Intake Since the Prepubertal Age May Contribute to the Pathogenesis of Endometriosis in Adulthood

High prevalence of endometriosis was reported in Asian women as a result of their traditionally high intake of soy foods during infancy. Soy is widely used in infant feeding after weaning from breast milk or cow milk. This study thus aimed to determine to what extent soy intake before puberty may contribute to the development of endometriosis. For this purpose, immature (6-week old) female rats were fed with various soy formulas (0%, 10%, 20%, 30%, 40%, 50%, and 60%). Normal control animals were fed with a soy-free diet. At 13 weeks of age, animals (except the normal control) underwent a transplantation surgery to establish endometriosis. Estradiol valerate and oxytocin were used to induce pelvic pain. Endometrial implant levels of glutathione (GSH) and malondialdehyde (MDA) allowed estimating tissue oxidative status. Physiological ovarian function was assessed by histological analysis of ovaries. Results showed that soy-fed animals grew faster than animals receiving a soy-free diet (P < .001). In animals supplemented with more than 10% of soy, the intensity of pelvic pain increased (P < .001) as well as the volume of ectopic foci. In addition, tissue levels of MDA and GSH increased (P < .001). The ovarian function was altered and the number of luteinized unruptured follicles increased. In conclusion, although animals supplemented with soy at the prepubertal stage displayed a good growth performance, regular soy consumption may promote the development and progress of endometriosis in adulthood, especially when soy content in food is more than 10%.

Influence of early-life factors on the development of endometriosis

Objective: Our aim was to study the association between early-life factors and the development of endometriosis. Methods: This case-control study included 440 women with surgically confirmed endometriosis (cases) and 880 women without endometriosis (controls). Information on early-life factors was ascertained retrospectively by in-person interviews with participants and their mothers. Adjusted odds ratios (ORs) and 95% confidence intervals (CIs) for the associations between endometriosis and maternal and paternal characteristics and foetal and infant exposures were estimated using unconditional logistic regression, adjusting for frequency matching and confounding variables. Results: We observed that women who were not breastfed as infants had twice the risk of endometriosis compared with women who were breastfed (adjusted OR 2.0; 95% CI 1.6, 4.5). Our data suggested an increased endometriosis risk with neonatal vaginal bleeding (adjusted OR 1.9; 95% CI 1.2, 4.3) and paternal smoking (adjusted OR 1.8; 95% CI 1.1, 4.9). Although the CIs included the null hypothesis value, caesarean section (adjusted OR 1.7; 95% CI 1.0, 3.5) and prematurity (adjusted OR 1.4; 95% CI 0.8, 3.7) were probably associated with the incidence of endometriosis. Conclusions: Some early-life factors including breastfeeding, neonatal vaginal bleeding and paternal smoking were associated with subsequent, surgically confirmed endometriosis in this cohort of Chinese women.

Developmental origins of endometriosis: a Swedish cohort study

BACKGROUND

Endometriosis is a chronic condition affecting women of reproductive age and is associated with multiple health burdens. Yet, findings regarding its 'developmental origins' are inconsistent. We aimed to investigate the associations of birth characteristics with endometriosis. We also explored potential mediation by adult social and reproductive factors.

METHODS

This cohort study consisted of 3406 women born in Uppsala, Sweden, between 1933 and 1972. We used data from archived birth records and endometriosis diagnoses at ages 15-50 recorded in the national patient registers. Socioeconomic and reproductive characteristics were obtained from routine registers. HRs were estimated from Cox regression.

RESULTS

During the follow-up, 111 women have been diagnosed with endometriosis, and most cases are external endometriosis (ie, outside the uterus, n=91). Lower standardised birth weight for gestational age was associated with increased rate of endometriosis (HR 1.35 per standard deviation decrease; 95% CI 1.08 to 1.67). This increased rate was also detected among women with fewer number of live births (HR 2.38; 95% CI 1.40 to 4.07 for one child vs ≥2 children; HR 6.09; 95% CI 3.88 to 9.57 for no child vs ≥2 children) and diagnosed infertility problem (HR 2.00; 95% CI 1.10 to 3.61) prior to endometriosis diagnosis. All the observed associations were stronger for external endometriosis. However, no evidence was found that number of births was the mediator of the inverse association between standardised birth weight and endometriosis.

CONCLUSION

This study supports the developmental origins theory and suggests that exposure to growth restriction during the fetal period is associated with increased risk of endometriosis during reproductive years.

The association between body mass index and the risk of endometriosis: A meta-analysis

Background:

Many epidemiologic studies have been conducted to assess factors that were associated to endometriosis, but there is no consistency in results. Therefore, we conducted this meta-analysis to investigate the association between body mass index and the risk of endometriosis.

Methods:

In this meta-analysis, relevant studies that published in major international electronic bibliographic databases of PubMed, Scopus and Web of Science were systematically searched during November 2017. The Begg and Egger’s test was used to investigate publication bias in included studies. The Q-statistic and I2 tests were carried out for measuring heterogeneity. The random-effects model was conducted to obtain pooled odds ratio.

Results:

Our results showed a direct association between underweight and endometriosis in woman (odds ratio = 1.41, 95% confidence interval = 1.16–1.66), so underweight woman had 41% higher chance for endometriosis. However, we did not find linear association between overweight and endometriosis (odds ratio = 0.95; 95% confidence interval: 0.72–1.18) and obesity and endometriosis (odds ratio = 0.88; 95% confidence interval: 0.54–1.21), respectively.

Conclusions:

Our results suggested that underweight was a risk factor for the endometriosis, while overweight and obesity were not protective factors for endometriosis.

Standard and Specialized Infant Formulas in Europe: Making, Marketing, and Health Outcomes

Infant formulas are the only suitable substitute for human milk. The most common infant formulas are standard formulas based on cow's milk. In addition, there are formulas for infants showing signs and symptoms of intolerance and for clinical conditions such as allergy, prematurity, and gastrointestinal diseases. A comprehensive review of the literature was made to review the composition of standard and specialized infant formulas and analyze indications for use, real or presumed nutrition differences and properties, and impact on infant growth. A brief consideration on costs is outlined for each formula. Over the past few years, industrial production and advertising of infant formulas have increased. Human milk still remains the most complete source of nutrition for infants and should be continued according to the current recommendations. Few differences exist between infant formulas, both for the nutrition action and the macronutrient/micronutrient composition. Specialized infant formulas have limited indications for use and high costs. The role of the pediatrician is crucial in the management of infant nutrition, promotion of breastfeeding, and prescribing of specialized formulas only in specific clinical conditions.

Not Having Been Breastfed May Protect Chinese Women From Developing Deep Infiltrating Endometriosis: Results From Subgroup Analyses of the FEELING Study

Background:

This study aimed to investigate potential factors, especially early-life exposures, associated with endometrioma (OMA) and/or deep infiltrating endometriosis (DIE) in Chinese women.

Methods:

This is a subgroup analyses of the FEELING study, which was a case–control study that investigated the clinical, lifestyle, and environmental factors associated with OMA and/or DIE in China, Russia, and France. In this subgroup analysis, the data for the Chinese participants were further analyzed using logistic regression model.

Results:

All women (N = 546) had fully completed the questionnaire. The mean age of the participants was 31.8 (range: 18-41) years. Univariable analysis showed that noncyclic chronic pelvic pain, dysmenorrhea intensity class, and whether breastfed during infancy were distributed differently between patients with OMA or DIE and those with no endometriosis (non-EM) or superficial peritoneal endometriosis (SUP; P < .05). Multivariable analysis revealed that not having been breastfed was a protective factor against OMA and DIE (odds ratio [OR] = 0.33, 95% confidence interval [CI]: 0.16-0.69). Further analysis indicated not having been breastfed was a protective factor for DIE compared with non-EM (OR = 0.13, 95% CI: 0.02-0.88) and with OMA + SUP (OR = 0.19, 95% CI: 0.04-0.85) but was not a protective factor for OMA compared with non-EM (OR = 0.66, 95% CI: 0.32-1.36) and with SUP (OR = 0.63, 95% CI: 0.31-1.30).

Conclusion:

This is the first study suggesting that not having been breastfed might protect against DIE in Chinese women.

Risk for and consequences of endometriosis: A critical epidemiologic review

Endometriosis affects approximately 10% of women of reproductive age. Characteristics robustly associated with a greater risk for endometriosis include early age at menarche, short menstrual cycle length, and lean body size, whereas greater parity has been associated with a lower risk. Relationships with other potential characteristics including physical activity, dietary factors, and lactation have been less consistent, partially because of the need for rigorous data collection and a longitudinal study design. Critical methodologic complexities include the need for a clear case definition; valid selection of comparison/control groups; and consideration of diagnostic bias and reverse causation when exploring demographic characteristics, medical history, and lifestyle factors. Reviewers and editors must demand a detailed description of rigorous methods to facilitate comparison and replication to advance our understanding of endometriosis.

A Longitudinal Study of Estrogen-Responsive Tissues and Hormone Concentrations in Infants Fed Soy Formula

PURPOSE

Chemicals with hormonelike activity, such as estrogenic isoflavones, may perturb human development. Infants exclusively fed soy-based formula are highly exposed to isoflavones, but their physiologic responses remain uncharacterized. Estrogen-responsive postnatal development was compared in infants exclusively fed soy formula, cow-milk formula, and breast milk.

METHODS

We enrolled 410 infants born in Philadelphia-area hospitals between 2010 and 2014; 283 were exclusively fed soy formula (n = 102), cow-milk formula (n = 111), or breast milk (n = 70) throughout the study (birth to 28 or 36 weeks for boys and girls, respectively). We repeatedly measured maturation index (MI) in vaginal and urethral epithelial cells using standard cytological methods, uterine volume and breast-bud diameter using ultrasound, and serum estradiol and follicle-stimulating hormone levels. We estimated MI, organ-growth, and hormone trajectories by diet using mixed-effects regression splines.

RESULTS

Maternal demographics did not differ between cow-milk-fed and soy-fed infants but did differ between formula-fed and breastfed infants. Vaginal-cell MI trended higher (P = 0.01) and uterine volume decreased more slowly (P = 0.01) in soy-fed girls compared with cow-milk-fed girls; however, their trajectories of breast-bud diameter and hormone concentrations did not differ. We observed no significant differences between boys fed cow-milk vs soy formula; estradiol was not detectable. Breastfed infants differed from soy-formula-fed infants in vaginal-cell MI, uterine volume, and girls' estradiol and boys' breast-bud diameter trajectories.

CONCLUSIONS

Relative to girls fed cow-milk formula, those fed soy formula demonstrated tissue- and organ-level developmental trajectories consistent with response to exogenous estrogen exposure. Studies are needed to further evaluate the effects of soy on child development.

Association between body mass index and endometriosis risk: a meta-analysis

Background

Epidemiological studies have sought to establish a relationship between a woman's current body mass index and endometriosis, but with varying results. This meta-analysis was to summarize the current epidemiological evidence.

Methods

Pertinent studies were identified by searching PubMed and Web of Science through November 2016. Study-specific risk estimates were combined using fixed or random effects models depending on whether significant heterogeneity was detected.

Results

A total of 11 studies (two cohort studies and nine case-control studies) was included in the meta-analysis. The pooled relative risk of endometriosis was 0.67 (95% CI: 0.53, 0.84) for each 5 kg/m² increase in current body mass index, with statistical significant heterogeneity across the studies (P <0.001, I² =86.9%). Compared with normal weight women, the pooled relative risk for obese women was 0.89 (95% CI: 0.83, 0.96), which was lower than that for overweight women (relative risk =0.97; 95% CI: 0.91, 1.05). The combined estimate was robust across subgroup and sensitivity analyses and no observed publication bias was detected.

Conclusion

This study suggested that higher body mass index may be associated with lower risk of endometriosis. Further work will need to focus on elucidating underlying biologic mechanism that contribute to the initiation of endometriosis.

Neonatal Genistein Exposure and Glucocorticoid Signaling in the Adult Mouse Uterus

BACKGROUND

Female reproductive tract development is sensitive to the endocrine-disrupting potential of environmental estrogens. Early-life exposure to the dietary phytoestrogen genistein impairs fertility and persistently alters the transcriptome in the oviduct and uterus of rodents. Glucocorticoid signaling, which has recently been shown to be essential for normal fertility in the female mouse uterus, is antagonized by genistein.

OBJECTIVE

Our goal was to determine whether early-life exposure to genistein disrupts glucocorticoid signaling in the mouse uterus, which may contribute to infertility.

METHODS

Female C57Bl/6 mice were exposed to either 50 mg/kg per day genistein, 10 μg/kg per day estradiol, or vehicle (corn oil) on postnatal days 1-5 (PND1-5), and then treated with the synthetic glucocorticoid dexamethasone (Dex: 1 mg/kg) or vehicle (saline) on PND5, at weaning on PND21, or as adults on PND56 following adrenalectomy and ovariectomy to evaluate glucocorticoid responsiveness. Uteri were isolated following treatment for gene expression or chromatin immunoprecipitation.

RESULTS

Neonatal exposure to genistein altered the uterine transcriptome of adult mice and caused substantial changes to the transcriptional response to glucocorticoids. Although expression of the glucocorticoid receptor was not affected, genistein exposure disrupted glucocorticoid receptor recruitment to specific regulatory sites in target genes. Many genes involved in chromatin remodeling were dysregulated in genistein-exposed mice, suggesting that epigenetic reprograming may contribute to the altered glucocorticoid response of the uterus following early-life exposure to genistein. These changes affected the biological activity of glucocorticoids within the uterus, as glucocorticoids antagonized the proliferative effects of estradiol in the uterus of control mice but not genistein-exposed mice.

CONCLUSIONS

Our findings suggest that disruption of glucocorticoid signaling due to early-life exposure to environmental estrogens may in part render the uterus unable to support implantation. https://doi.org/10.1289/EHP1575.

A focus on the distinctions and current evidence of endometriosis in adolescents

Endometriosis (EM) occurring in adolescents presents distinct clinical and histologic characteristics compared to the disease in women. Because the symptoms of EM are nonspecific, often overlapping with those experienced in a range of gynecological and gastrointestinal conditions, the process of reaching a diagnosis of EM is often delayed. The diagnosis of EM is suspected depending on the history and the symptoms and signs, is corroborated by physical examination and imaging techniques, and is finally proved by histological examination of specimens collected during laparoscopy. Currently, there is insufficient evidence to make strong recommendations for management in adolescents who may have EM. This short report reviews some peculiarities of EM in adolescents and provides an update of recent knowledge of the diagnosis and treatment of EM. We hope that the present contribution may help to bring more attention to the clinical diagnosis of EM and consequently aid in decreasing diagnostic delay.

Endometriosis in Adolescent and Young Girls: Report on a Series of 55 Cases

STUDY OBJECTIVE

The aim of this retrospective study was to evaluate endometriosis in adolescent and young girls and further to review the menstrual, reproductive characteristics, and risk factors.

DESIGN AND SETTING

We reviewed the medical records of adolescent and young girls with endometriosis from 2 different countries. Data were collected and analyzed from charts of 900 patients with endometriosis.

PARTICIPANTS AND INTERVENTIONS

Fifty-five female adolescents aged between 13 and 21 years (mean age 18.3 years) participated in our series. This study was conducted in the Obstetric and Gynecology Department of Venizeleio General Hospital of Crete and involved all patients diagnosed with endometriosis between 1996 and 2016.

MAIN OUTCOME MEASURES

Statistical methods included χ² and Mann-Whitney U test.

RESULTS

Of 900 patients with endometriosis we found 55 female adolescents (6.1%). The mean age was 18.3 ± 2.3 years, significantly younger compared with the advanced endometriosis patients (32.7 ± 7.2; P < .001). Regarding the menstrual reproductive and others characteristics, we observed several differences in adolescent young girls compared with the advanced age endometriosis group. The factors associated with an increased risk for young women include age at menarche, dysmenorrhea, history of asthma, and a positive family history of endometriosis. Additionally, we report on 16 of 55 (32%) adolescent women with endometriosis and congenital malformations (P < .01) and 5 patients who were diagnosed with dry eye syndrome.

CONCLUSION

There is an association between endometriosis in adolescent and young women and risk factors including early menarche, early onset of dysmenorrhea, history of asthma, previous surgical procedures, obstructive genital anomalies, and family history of endometriosis.

A higher prevalence of endometriosis among Asian women does not contribute to poorer IVF outcomes

PURPOSE

The purpose of the study was to determine whether diagnosis of endometriosis or endometriosis with endometrioma influences in vitro fertilization (IVF) outcomes in an ethnically diverse population.

METHODS

Women undergoing a first IVF cycle (n = 717) between January 1, 2008 and December 31, 2009, at a university-affiliated infertility clinic, were retrospectively assessed for an endometriosis diagnosis. Differences in prevalence of endometriosis by ethnicity were determined, as well as differences in IVF success by ethnicity, with a focus on country of origin for Asian women. A multivariate model was generated to assess the relative contributions of country of origin and endometriosis to chance of clinical pregnancy with IVF.

RESULTS

Endometriosis was diagnosed in 9.5% of participants; 3.5% also received a diagnosis of endometrioma. Endometriosis prevalence in Asian women was significantly greater than in Caucasians (15.7 vs. 5.8%, p < 0.01). Women of Filipino (p < 0.01), Indian (p < 0.01), Japanese (p < 0.01), and Korean (p < 0.05) origin specifically were more likely to have endometriosis than Caucasian women, although there was no difference in endometrioma presence by race/ethnicity. Oocyte quantity, embryo quality, and fertilization rates did not relate to endometriosis. Clinical pregnancy rates were significantly lower for Asian women, specifically in Indian (p < 0.05), Japanese (p < 0.05), and Korean (p < 0.05) women, compared to Caucasian women, even after controlling for endometriosis status.

CONCLUSIONS

The prevalence of endometriosis appears to be higher in Filipino, Indian, Japanese, and Korean women presenting for IVF treatment than for Caucasian women; however, the discrepancy in IVF outcomes was conditionally independent of the presence of endometriosis. Future research should focus on improving pregnancy outcomes for Asian populations whether or not they are affected by endometriosis, specifically in the form of longitudinal studies where exposures can be captured prior to endometriosis diagnoses and infertility treatment.

Soy Formula and Epigenetic Modifications: Analysis of Vaginal Epithelial Cells from Infant Girls in the IFED Study

BACKGROUND

Early-life exposure to estrogenic compounds affects the development of the reproductive system in rodent models and humans. Soy products, which contain phytoestrogens such as genistein, are one source of exposure in infants fed soy formula, and they result in high serum concentrations.

OBJECTIVES

Our goal was to determine whether soy exposure is associated with differential DNA methylation in vaginal cells from soy-fed infant girls.

METHODS

Using the Illumina HumanMethylation450 BeadChip, we evaluated epigenome-wide DNA methylation in vaginal cells from four soy formula-fed and six cow formula-fed girls from the Infant Feeding and Early Development (IFED) study. Using pyrosequencing we followed up the two most differentially methylated sites in 214 vaginal cell samples serially collected between birth and 9 months of age from 50 girls (28 soy formula-fed and 22 cow formula-fed). With a mouse model, we examined the effect of neonatal exposure to genistein on gene specific mRNA levels in vaginal tissue.

RESULTS

The epigenome-wide scan suggested differences in methylation between soy formula-fed and cow formula-fed infants at three CpGs in the gene proline rich 5 like (PRR5L) (p < 104). Pyrosequencing of the two feeding groups found that methylation levels progressively diverged with age, with pointwise differences becoming statistically significant after 126 days. Genistein-exposed mice showed a 50% decrease in vaginal Prr5l mRNA levels compared to controls.

CONCLUSIONS

Girls fed soy formula have altered DNA methylation in vaginal cell DNA which may be associated with decreased expression of an estrogen-responsive gene. Citation: Harlid S, Adgent M, Jefferson WN, Panduri V, Umbach DM, Xu Z, Stallings VA, Williams CJ, Rogan WJ, Taylor JA. 2017. Soy formula and epigenetic modifications: analysis of vaginal epithelial cells from infant girls in the IFED study. Environ Health Perspect 125:447-452; http://dx.doi.org/10.1289/EHP428.

Soy-Based Therapeutic Baby Formulas: Testable Hypotheses Regarding the Pros and Cons

Soy-based infant formulas have been consumed in the United States since 1909, and currently constitute a significant portion of the infant formula market. There are efforts underway to generate genetically modified soybeans that produce therapeutic agents of interest with the intent to deliver those agents in a soy-based infant formula platform. The threefold purpose of this review article is to first discuss the pros and cons of soy-based infant formulas, then present testable hypotheses to discern the suitability of a soy platform for drug delivery in babies, and finally start a discussion to inform public policy on this important area of infant nutrition.

Environmental factors, epigenetics, and developmental origin of reproductive disorders

Sex-specific differentiation, development, and function of the reproductive system are largely dependent on steroid hormones. For this reason, developmental exposure to estrogenic and anti-androgenic endocrine disrupting chemicals (EDCs) is associated with reproductive dysfunction in adulthood. Human data in support of "Developmental Origins of Health and Disease" (DOHaD) comes from multigenerational studies on offspring of diethylstilbestrol-exposed mothers/grandmothers. Animal data indicate that ovarian reserve, female cycling, adult uterine abnormalities, sperm quality, prostate disease, and mating behavior are susceptible to DOHaD effects induced by EDCs such as bisphenol A, genistein, diethylstilbestrol, p,p'-dichlorodiphenyl-dichloroethylene, phthalates, and polyaromatic hydrocarbons. Mechanisms underlying these EDC effects include direct mimicry of sex steroids or morphogens and interference with epigenomic sculpting during cell and tissue differentiation. Exposure to EDCs is associated with abnormal DNA methylation and other epigenetic modifications, as well as altered expression of genes important for development and function of reproductive tissues. Here we review the literature exploring the connections between developmental exposure to EDCs and adult reproductive dysfunction, and the mechanisms underlying these effects.

Endometriomas and deep infiltrating endometriosis in adulthood are strongly associated with anogenital distance, a biomarker for prenatal hormonal environment

STUDY QUESTION

Is the length of the anogenital distance (AGD), a biomarker of the in-utero prenatal hormonal environment, associated with the presence of endometriomas and deep infiltrating endometriosis (DIE)?

SUMMARY ANSWER

Shorter AGD is associated with presence of endometriomas and DIE.

WHAT IS KNOWN ALREADY

It is debated whether hormonal exposure to estrogens in utero may be a risk factor for endometriosis in adulthood. AGD is a biomarker of prenatal hormonal environment and observational studies have shown an association between AGD and reproductive parameters in both sexes.

STUDY DESIGN, SIZE, DURATION

This case–control study of 114 women with endometriosis (endometriomas and/or DIE) and 105 controls was conducted between September 2014 and May 2015.

PARTICIPANTS/MATERIALS, SETTING, METHODS

Cases were attending the Endometriosis Unit of the Hospital. Prevalent as well as incident cases, diagnosed by transvaginal ultrasound (TVUS), were included. Controls were women without endometriosis attending the gynecological outpatient clinic for routine gynecological exams. Participants completed health questionnaires, followed physical and gynecological examinations, including TVUS. Measurements from the anterior clitoral surface to the upper verge of the anus (AGD_AC), and from the posterior fourchette to the upper verge of the anus (AGD_AF) were obtained in all subjects. Unconditional multiple logistic regression was used to estimate the association between AGD measurements and presence of endometriomas and/or DIE while accounting for important confounders and covariates, including age, body mass index, vaginal delivery or episiotomy.

MAIN RESULTS AND THE ROLE OF CHANCE

AGD_AF was related to presence of endometriomas and/or DIE. For all cases of endometriosis (endometriomas and DIE), women in the lowest tertile of the AGD_AF distribution, compared with the upper tertile, were 7.6-times (95% CI 2.8–21.0; P-trend < 0.001) more likely to have endometriosis. With regard to DIE, women with AGD_AF below the median, compared with those with AGD_AF above the median, were 41.6-times (95% CI 3.9–438; P-value = 0.002) more likely to have endometriosis.

LIMITATIONS, REASONS FOR CAUTION

In case–control studies, information and selection bias has to be ruled out. Physicians conducting the measurement were blind to the status of the patients. Controls came from the same population as the cases. We adjusted for known and suspected confounders and covariates, but the possibility of residual confounding or chance findings should always be considered. As with all observational studies, causal inference is limited.

WIDER IMPLICATIONS OF THE FINDINGS

This study suggests that endometriosis, especially the DIE, might have a prenatal origin that may be traced back to the hormonal milieu in which the fetus develops.

STUDY FUNDING/COMPETING INTEREST

This work was supported by the Ministry of Economy and Competitiveness, ISCIII (AES), grant no. PI13/01237 and the Seneca Foundation, Murcia Regional Agency of Science and Technology, grant no. 19443/PI/14. The authors have no competing interests to declare.

TRIAL REGISTRATION NUMBER

Not applicable.

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