Dietary folate intake and modification of the association of urinary bisphenol A concentrations with in vitro fertilization outcomes among women from a fertility clinic

Antioxidant Intake and Ovarian Reserve in Women Attending a Fertility Center

BACKGROUND/OBJECTIVES

The aim of this study was to investigate the association between antioxidant intake and antral follicle count (AFC), a marker of ovarian reserve, in women attending a fertility clinic.

METHODS

We conducted an observational study with 567 women undergoing infertility evaluation at the Massachusetts General Hospital Fertility Center, who were enrolled in the Environment and Reproductive Health (EARTH) study. Participants filled out the lifestyle and health questionnaires and a validated food frequency questionnaire (FFQ) for assessing habitual dietary intake and underwent a transvaginal ultrasound to measure AFC. Intake of nutrients with direct antioxidant capacity (vitamin A, C, and E and carotenoids) and intake of antioxidant food sources were estimated from the FFQ. Adjusted Poisson regression models were fitted to assess the relationships between antioxidants and AFC while adjusting for potential confounders. Non-linearity was assessed with restricted cubic splines.

RESULTS

The median (interquartile range) age and AFC of participants were 35.0 (32.0-38.0) years and 13 (9-18), respectively. Our findings revealed a non-linear association between lycopene intake and AFC. There was a positive linear association with the highest AFC among women consuming approximately 6000 mcg/day of lycopene (p for non-linearity = 0.003). An inverse association was observed between retinol intake, predominantly from dairy foods, and AFC among women aged under 35 years (p-trend < 0.001 and 0.01, respectively).

CONCLUSIONS

Our findings suggest that lycopene intake might influence the ovarian reserve in fertility patients. The observed inverse association with retinol, if confirmed, may reflect biological mechanisms different from oxidative stress. The underlying mechanisms of these associations remain to be elucidated and warrant further investigation.

Effect of exposure to environmental phenols and parabens on folate concentrations among 3-19 years old children and adolescents: A cross-sectional study in NHANES 2005-2016

Phenols and parabens, as endocrine-disrupting chemicals (EDCs), are prevalent in daily consumer products and industrial applications. Folate, a vital vitamin, plays a crucial role in numerous metabolic processes. The interaction between EDCs and folate is not well understood and warrants investigation. We utilized data from the National Health and Nutrition Examination Survey (NHANES) 2005-2016. Since many pollutants are co-exposed congeners, with interactive effects between pollutants, we employed multivariate linear regression model, weighted quantile sum regression, and Bayesian kernel machine regression (BKMR) to quantify the impact of folate levels in serum and red blood cell (RBC) and the overall effects of combined exposures. The study included 4395 children and adolescents. A negative correlation was observed between RBC folate concentrations and urinary concentrations of Bisphenol A (BPH), Triclosan (TRS), Methyl paraben (MPB), Propyl paraben (PPB), and Butyl paraben (BUP), in children and adolescents. Specifically, an increase in RBC folate levels was linked to a decrease in urinary BPH, TRS, MPB, PPB, and BUP concentrations. Similar associations were found with serum folate. The weighted quantile sum index showed a decrease in both RBC and serum folate levels with an increase in the mixture of phenols and parabens. BKMR further supported the overall negative impact of the chemical mixture on folate levels. This study provides evidence of an inverse relationship between exposure to phenols and parabens and folate concentrations in children and adolescents, which would be of significance in providing guidance for clinical interventions and calling for remediation actions to be prioritized during childhood.

Nutritional Changes to Improve Female Fertility: Role of Obesity, Hormones, Dietary Patterns and Endocrine Disrupting Chemicals

Importance

Infertility affects around 180 million people in the world and can be influenced by a number of nutritional factors.

Objective

The idea of a pretreatment optimization including beneficial weight loss, adequate physical activity, and good lifestyle habits could enhance fertility for many couples who want to conceive a baby.

Results

There are different aspects related to nutrition, such as obesity (affecting 23%-30% of reproductive-aged women), dietary patterns (type of diet, good or bad habits, and physical activity), nutrients (vitamins or minerals), hormones (adipokines, among others), and endocrine-disrupting chemicals (phytoestrogens and bisphenol A, among others) that have a clear impact on women's fertility.

Evidence Acquisition

Findings have shown that a Mediterranean or balanced diet with an adequate weight loss in case of obesity and an appropriate serum concentration of different nutrients with low endocrine-disrupting exposure could improve female fertility. In addition, the context is quite important, as there are many differences between overweight and low-weight women, and both can encounter difficulties conceiving.

Conclusions and Relevance

The aim of this review is to elucidate the impact of obesity and hormones in women's fertility. In addition, how dietary patterns could help people to increase probability of conception and birth using less fertility treatments cycles will be also analyzed. Moreover, the role of endocrine-disrupting chemicals, pollutants, and contaminants will be discussed.

Environmental Hazards and Male Fertility: Why Don't We Know More?

Nearly all (97%) the studies in the recent literature addressing the relationship between environmental hazards and male fertility use at least one of three common study design strategies: recruiting men presenting to fertility centers (53%), evaluating only one environmental exposure at a time (87%), and using conventional semen quality parameters as the only study outcome (45%). While each of these study design features is logical, defensible, and has generated an enormous amount of information regarding the impact of the environment on male reproductive function, they may also be barriers to furthering our understanding. In this article, we examine in which ways each of these study design features limits progress on male fertility research and propose strategies to go beyond them. Rather than abandoning these strategies, we propose that they should be a starting point instead of the default strategy for the future of male fertility research to more fully understand how men's environmental exposures impact human fertility and human reproduction more generally.

Impact of Bisphenol A and its alternatives on oocyte health: a scoping review

BACKGROUND

Bisphenol A (BPA) is an endocrine disrupting chemical released from plastic materials, including food packaging and dental sealants, persisting in the environment and ubiquitously contaminating ecosystems and human populations. BPA can elicit an array of damaging health effects and, alarmingly, 'BPA-free' alternatives mirror these harmful effects. Bisphenol exposure can negatively impact female fertility, damaging both the ovary and oocytes therein. Such damage can diminish reproductive capacity, pregnancy success, and offspring health. Despite global government regulations in place to indicate 'safe' BPA exposure levels, these policies have not considered the effects of bisphenols on oocyte health.

OBJECTIVE AND RATIONALE

This scoping review was conducted to evaluate evidence on the effects of BPA and BPA alternatives on standardized parameters of oocyte health. In doing so, this review addresses a critical gap in the literature providing a comprehensive, up-to-date synthesis of the effects of bisphenols on oocyte health.

SEARCH METHODS

This scoping review was conducted in accordance with PRISMA guidelines. Four databases, Medline, Embase, Scopus, and Web of Science, were searched twice (23 February 2022 and 1 August 2023) to capture studies assessing mammalian oocyte health post-bisphenol exposure. Search terms regarding oocytes, ovarian follicles, and bisphenols were utilized to identify relevant studies. Manuscripts written in English and reporting the effect of any bisphenol on mammalian oocyte health from all years were included. Parameters for toxicological studies were evaluated, including the number of bisphenol concentrations/doses tested, dosing regimen, biological replicates and/or animal numbers, and statistical information (for human studies). Standardized parameters of oocyte health including follicle counts, oocyte yield, oocyte meiotic capacity, morphology of oocyte and cumulus cells, and oocyte meiotic spindle integrity were extracted across the studies.

OUTCOMES

After screening 3147 studies, 107 studies of either humans or mammalian animal models or humans were included. Of the in vitro exposure studies, 96.3% (26/27) and 94.1% (16/17) found at least one adverse effect on oocyte health using BPA or BPA alternatives (including BHPF, BPAF, BPB, BPF, and BPS), respectively. These included increased meiotic cell cycle arrest, altered morphology, and abnormal meiotic spindle/chromosomal alignment. In vivo, 85.7% (30/35) of studies on BPA and 92.3% (12/13) on BPA alternatives documented adverse effects on follicle development, morphology, or spindle/chromosome alignment. Importantly, these effects were recorded using levels below those deemed 'safe' for human exposure. Over half (11/21) of all human observational studies showed associations between higher urinary BPA levels and reduced antral follicle counts or oocyte yield in IVF patients. Recommendations are presented based on the identified shortcomings of the current evidence, incorporating elements of FDA requirements for future research in the field.

WIDER IMPLICATIONS

These data highlight the detrimental impacts of low-level BPA and BPA alternative exposure, contributing to poor oocyte quality and reduced fertility. These outcomes are valuable in promoting the revision of current policies and guidelines pertaining to BPA exposure internationally. This study serves as a valuable resource to scientists, providing key recommendations on study design, reporting elements, and endpoint measures to strengthen future studies. Ultimately, this review highlights oocyte health as a fundamentally important endpoint in reproductive toxicological studies, indicating an important direction for future research into endocrine disrupting chemicals to improve fertility outcomes.

Mixtures of Urinary Phenol and Phthalate Metabolite Concentrations in Relation to Serum Lipid Levels among Pregnant Women: Results from the EARTH Study

We examined whether mixtures of urinary concentrations of bisphenol A (BPA), parabens and phthalate metabolites were associated with serum lipid levels among 175 pregnant women who enrolled in the Environment and Reproductive Health (EARTH) Study (2005-2017), including triglycerides, total cholesterol, high-density lipoprotein (HDL), non-HDL, and low-density lipoprotein (LDL). We applied Bayesian Kernel Machine Regression (BKMR) and quantile g-computation while adjusting for confounders. In the BKMR models, we found no associations between chemical mixture and lipid levels, e.g., total cholesterol [mean difference (95% CRI, credible interval) = 0.02 (-0.31, 0.34)] and LDL [mean difference (95% CRI) = 0.10 (-0.22, 0.43)], when comparing concentrations at the 75th to the 25th percentile. When stratified by BMI, we found suggestive positive relationships between urinary propylparaben and total cholesterol and LDL among women with high BMI [mean difference (95% CRI) = 0.25 (-0.26, 0.75) and 0.35 (-0.25, 0.95)], but not with low BMI [mean difference (95% CRI) = 0.00 (-0.06, 0.07) and 0.00 (-0.07, 0.07)]. No association was found by quantile g-computation. This exploratory study suggests mixtures of phenol and phthalate metabolites were not associated with serum lipid levels during pregnancy, while there were some suggestive associations for certain BMI subgroups. Larger longitudinal studies with multiple assessments of both exposure and outcome are needed to corroborate these novel findings.

Does Bisphenol-A play a role in the development of neural tube defects?

OBJECTIVE

In this study, we aimed to evaluate BPA levels in the maternal serum and amniotic fluid of patients diagnosed with NTD. In addition, we wanted to investigate the relationship between neurodevelopmental defects, such as neural tube defects (NTD), and BPA levels.

STUDY DESIGN

This prospective observational study was carried out at Bursa Yüksek İhtisas Training and Research Hospital between April 15, 2021, and April 15, 2022. The study consisted of 92 patients between the ages of 18-45 who had an amniocentesis at 15-22 weeks of gestation. The patients were divided into two groups according to the indications of amniocentesis. Group 1 contained the patients with abnormal maternal serum screening results or cell-free DNA results and abnormal ultrasonography findings (45 patients). Group 2 contained the patients with a pre-diagnosis of NTD (47 patients). The first 5 cc fluids and maternal serum samples taken during the amniocentesis procedure of all patients were delivered to the biochemistry laboratory. The BPA values between groups were compared.

RESULTS

A statistically significant difference was found between the two groups in terms of amniotic fluid BPA levels (36.66 (19.00:82.00) and 39.62 (19.02-73.87)) and maternal blood BPA levels (22.26 (12.60-228) and 47.81 (12.89-228.39)). In cases with NTD, amniotic fluid BPA levels and maternal blood BPA levels were significantly higher than the control group. When AUC values were compared, the AFP numerical value was higher than the amniotic fluid and maternal blood BPA levels.

CONCLUSION

Plastic, which is indispensable for modern life, may negatively affect fetal development in intrauterine life. The data in this study says that high maternal blood BPA may be associated with NTD.

The Role of One-Carbon Metabolism and Methyl Donors in Medically Assisted Reproduction: A Narrative Review of the Literature

One-carbon (1-C) metabolic deficiency impairs homeostasis, driving disease development, including infertility. It is of importance to summarize the current evidence regarding the clinical utility of 1-C metabolism-related biomolecules and methyl donors, namely, folate, betaine, choline, vitamin B12, homocysteine (Hcy), and zinc, as potential biomarkers, dietary supplements, and culture media supplements in the context of medically assisted reproduction (MAR). A narrative review of the literature was conducted in the PubMed/Medline database. Diet, ageing, and the endocrine milieu of individuals affect both 1-C metabolism and fertility status. In vitro fertilization (IVF) techniques, and culture conditions in particular, have a direct impact on 1-C metabolic activity in gametes and embryos. Critical analysis indicated that zinc supplementation in cryopreservation media may be a promising approach to reducing oxidative damage, while female serum homocysteine levels may be employed as a possible biomarker for predicting IVF outcomes. Nonetheless, the level of evidence is low, and future studies are needed to verify these data. One-carbon metabolism-related processes, including redox defense and epigenetic regulation, may be compromised in IVF-derived embryos. The study of 1-C metabolism may lead the way towards improving MAR efficiency and safety and ensuring the lifelong health of MAR infants.

Women's preconception psychological stress and birth outcomes in a fertility clinic: the EARTH study

Background

The epidemiologic literature on women's perceived stress in relation to perinatal outcomes has been inconclusive and does not consider the preconception window of exposure.

Objective

To evaluate whether women's preconception perceived stress is related to live birth, gestational age, and birthweight in a cohort receiving fertility treatment.

Methods

This observational study included women seeking fertility care at the Massachusetts General Hospital (2004-2019). During preconception, women provided information on their psychological stress using the short version of the validated Perceived Stress Scale 4 (PSS-4). We used regression models to evaluate the associations of stress with live birth (N = 768 attempting to conceive) and perinatal outcomes (N = 413 live births) while adjusting for confounders. Stratified analyses by mode of conception [natural, intrauterine insemination (IUI), and IVF (in vitro fertilization)] and selected socioeconomic factors (race, education, and income) were also conducted.

Results

Higher psychological stress was negatively associated with the overall probability of live birth (adjusted RR = 0.95, 95% CI: 0.92, 0.98), particularly among women conceiving using IVF. However, we found no association between women's psychological stress and gestational age and birth weight in the overall analyses and also stratified by mode of conception. Similarly, we observed no differences in women's psychological stress with any of the measured outcomes by socioeconomic factors.

Discussion

These results highlight the importance of considering the preconception window and mode of conception when evaluating the relationship between women's preconception stress and live birth.

Preconception Stress and Pregnancy Serum Glucose Levels Among Women Attending a Fertility Center

Context

The association between women's stress and pregnancy glucose levels remain unclear, specifically when considering the preconception period as a sensitive window of exposure.

Objective

We investigated whether preconception perceived stress was associated with glucose levels during pregnancy among women attending a fertility center (2004-2019).

Methods

Before conception, women completed a psychological stress survey using the short version of the validated Perceived Stress Scale 4 (PSS-4), and blood glucose was measured using a 50-gram glucose load test during late pregnancy as a part of screening for gestational diabetes. Linear and log-binomial regression models were used to assess associations of total PSS-4 scores with mean glucose levels and abnormal glucose levels ( ≥ 140 mg/dL), adjusting for age, body mass index, race, smoking, education, physical activity, primary infertility diagnosis, number of babies, and mode of conception.

Results

Psychological stress was positively associated with mean abnormal glucose levels. The adjusted marginal means (95% CI) of mean glucose levels for women in the first, second, and third tertiles of psychological stress were 115 (110, 119), 119 (115, 123), and 124 (119, 128), and mg/dL, respectively (P for trend = .007). Also, women in the second and third tertiles of psychological stress had 4% and 13% higher probabilities of having abnormal glucose compared with women in the first tertile of psychological stress (P trend = .01).

Conclusion

These results highlight the importance of considering preconception when evaluating the relationship between women's stress and pregnancy glucose levels.

Mixtures of urinary concentrations of phenols and phthalate biomarkers in relation to the ovarian reserve among women attending a fertility clinic

Although prior studies have found associations of the ovarian reserve with urinary concentrations of some individual phenols and phthalate metabolites, little is known about the potential associations of these chemicals as a mixture with the ovarian reserve. We investigated whether mixtures of four urinary phenols (bisphenol A, butylparaben, methylparaben, propylparaben) and eight metabolites of five phthalate diesters including di(2-ethylhexyl) phthalate were associated with markers of the ovarian reserve among 271 women attending a fertility center who enrolled in the Environment and Reproductive Health study (2004-2017). The analysis was restricted to one outcome per study participant using the earliest outcome after the last exposure assessment. Ovarian reserve markers included lower antral follicle count (AFC) defined as AFC < 7, circulating serum levels of day 3 follicle stimulating hormone (FSH) assessed by immunoassays, and diminished ovarian reserve (DOR) defined as either AFC < 7, FSH > 10 UI/L or primary infertility diagnosis of DOR. We applied Bayesian Kernel Machine Regression (BKMR) and quantile g-computation to estimate the joint associations and assess the interactions between chemical exposure biomarkers on the markers of the ovarian reserve while adjusting for confounders. Among all 271 women, 738 urine samples were collected. In quantile g-computation models, a quartile increase in the exposure biomarkers mixture was not significantly associated with lower AFC (OR = 1.10, 95 % CI = 0.52, 2.30), day 3 FSH levels (Beta = 0.30, 95 % CI = -0.32, 0.93) or DOR (OR = 1.02, 95 % CI = 0.52, 2.05). Similarly, BKMR did not show any evidence of associations between the mixture and any of the studied outcomes, or interactions between chemicals. Despite the lack of associations, these results need to be explored among women in other study cohorts.

Temporal trends in urinary concentrations of phenols, phthalate metabolites and phthalate replacements between 2000 and 2017 in Boston, MA

Endocrine disrupting chemicals (EDCs) can adversely affect human health and are ubiquitously found in everyday products. We examined temporal trends in urinary concentrations of EDCs and their replacements. Urinary concentrations of 11 environmental phenols, 15 phthalate metabolites, phthalate replacements such as two di(isononyl)cyclohexane-1,2-dicarboxylate (DINCH) metabolites, and triclocarban were quantified using isotope-dilution tandem mass spectrometry. This ecological study included 996 male and 819 female patients who were predominantly White/Caucasian (83 %) with an average age of 35 years and a BMI of 25.5 kg/m2 seeking fertility treatment in Boston, MA, USA. Patients provided a total of 6483 urine samples (median = 2, range = 1-30 samples per patient) between 2000 and 2017. Over the study period, we observed significant decreases (% per year) in urinary concentrations of traditional phenols, parabens, and phthalates such as bisphenol A (β: -6.3, 95 % CI: -7.2, -5.4), benzophenone-3 (β: -6.5, 95 % CI: -1.1, -18.9), parabens ((β range:-5.4 to -14.2), triclosan (β: -18.8, 95 % CI: -24, -13.6), dichlorophenols (2.4-dichlorophenol β: -6.6, 95 % CI: -8.8, -4.3); 2,5-dichlorophenol β: -13.6, 95 % CI: -17, -10.3), di(2-ethylhexyl) phthalate metabolites (β range: -11.9 to -22.0), and other phthalate metabolites including mono-ethyl, mono-n-butyl, and mono-methyl phthalate (β range: -0.3 to -11.5). In contrast, we found significant increases in urinary concentrations of environmental phenol replacements including bisphenol S (β: 3.9, 95 % CI: 2.7, 7.6) and bisphenol F (β: 6, 95 % CI: 1.8, 10.3), DINCH metabolites (cyclohexane-1,2-dicarboxylic acid monohydroxy isononyl ester [MHiNCH] β: 20, 95 % CI: 17.8, 22.2; monocarboxyisooctyl phthalate [MCOCH] β: 16.2, 95 % CI: 14, 18.4), and newer phthalate replacements such as mono-3-carboxypropyl phthalate, monobenzyl phthalate, mono-2-ethyl-5-carboxypentyl phthalate and di-isobutyl phthalate metabolites (β range = 5.3 to 45.1), over time. Urinary MHBP concentrations remained stable over the study period. While the majority of biomarkers measured declined over time, concentrations of several increased, particularly replacement chemicals that are studied.

Associations of Maternal Urinary Concentrations of Phenols, Individually and as a Mixture, with Serum Biomarkers of Thyroid Function and Autoimmunity: Results from the EARTH Study

The associations between urinary phenol concentrations and markers of thyroid function and autoimmunity among potentially susceptible subgroups, such as subfertile women, have been understudied, especially when considering chemical mixtures. We evaluated cross-sectional associations of urinary phenol concentrations, individually and as a mixture, with serum markers of thyroid function and autoimmunity. We included 339 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2009-2015). We quantified four phenols in urine using isotope dilution high-performance liquid chromatography-tandem mass spectrometry, and biomarkers of thyroid function (thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4), and triiodothyronine (fT3, TT3)), and autoimmunity (thyroid peroxidase (TPO) and thyroglobulin (Tg) antibodies (Ab)) in serum using electrochemoluminescence assays. We fit linear and additive models to investigate the association between urinary phenols-both individually and as a mixture-and serum thyroid function and autoimmunity, adjusted for confounders. As a sensitivity analysis, we also applied Bayesian Kernel Machine Regression (BKMR) to investigate non-linear and non-additive interactions. Urinary bisphenol A was associated with thyroid function, in particular, fT3 (mean difference for a 1 log unit increase in concentration: -0.088; 95% CI [-0.151, -0.025]) and TT3 (-0.066; 95% CI [-0.112, -0.020]). Urinary methylparaben and triclosan were also associated with several thyroid hormones. The overall mixture was negatively associated with serum fT3 concentrations (mean difference comparing all four mixture components at their 75th vs. 25th percentiles: -0.19, 95% CI [-0.35, -0.03]). We found no evidence of non-linearity or interactions. These results add to the current literature on phenol exposures and thyroid function in women, suggesting that some phenols may alter the thyroid system.

Perceived stress and markers of ovarian reserve among subfertile women

RESEARCH QUESTION

Is self-reported psychological stress associated with markers of ovarian reserve among subfertile women?

DESIGN

Observational study of women (n = 520) seeking fertility care at the Massachusetts General Hospital who enrolled in the Environment and Reproductive Health study between 2005 and 2019. Women completed the short version of the validated PSS4, which assesses psychological stress. Ovarian reserve markers included AFC and circulating serum levels of day-3 FSH, with AMH assessed in a subset of participants (n = 185).

RESULTS

Higher total PSS4 scores were negatively associated with AFC and serum AMH levels. Analyses adjusted for age, BMI, race, smoking, education, physical activity and type of infertility diagnosis. Women in the second and third tertiles of stress had lower AFC (13.3, 95% CI 12.7 to 13.8; and 13.5, 95% CI 13.0 to 14.1) compared with women in the lowest tertile of psychological stress score (14.3, 95% CI 13.8 to 14.9, both P < 0.05). Women in the second and third tertiles of total PSS4 scores also had lower mean serum AMH compared with women in the lowest tertile (2.99, 95% CI 2.24 to 3.74), and (2.99 95% CI 2.22 to 3.76) versus (3.94 95% CI 3.23 to 4.64). These associations varied by several socioeconomic factors, and were observed among women who were younger, belonging to minority races, with a college degree or with annual household income less than $100,000.

CONCLUSIONS

Higher perceived stress was negatively associated with AFC and serum AMH levels. These associations varied by several socioeconomic factors.

Folate concentrations and serum perfluoroalkyl and polyfluoroalkyl substance concentrations in adolescents and adults in the USA (National Health and Nutrition Examination Study 2003-16): an observational study

BACKGROUND

Perfluoroalkyl and polyfluoroalkyl substances (PFAS) are a family of highly fluorinated aliphatic compounds, which are widely used in commercial applications, including food packaging, textiles, and non-stick cookware. Folate might counteract the effects of environmental chemical exposures. We aimed to explore the relationship between blood folate biomarker concentrations and PFAS concentrations.

METHODS

This observational study pooled cross-sectional data from the National Health and Nutrition Examination Survey (NHANES) 2003 to 2016 cycles. NHANES is a population-based national survey that measures the health and nutritional status of the US general population every 2 years by means of questionnaires, physical examination, and biospecimen collection. Folate concentrations in red blood cells and in serum, and perfluorooctanoic acid (PFOA), perfluorooctanesulfonic acid (PFOS), perfluorononanoic acid (PFNA), and perfluorohexane sulfonic acid (PFHxS) concentrations in serum were examined. We used multivariable regression models to assess the percentage change in serum PFAS concentrations in relation to changes in folate biomarker concentrations. We additionally used models with restricted cubic splines to investigate the shape of these associations.

FINDINGS

This study included 2802 adolescents and 9159 adults who had complete data on PFAS concentrations, folate biomarkers, and covariates, were not pregnant, and had never had a cancer diagnosis at the time of the survey. The mean age was 15·4 years (SD 2·3) for adolescents and 45·5 years (17·5) for adults. The proportion of male participants was slightly higher in adolescents (1508 [54%] of 2802 participants) than in adults (3940 [49%] of 9159 participants). We found negative associations between red blood cell folate concentrations and serum concentrations of PFOS (percentage change for a 2·7 fold-increase in folate level -24·36%, 95% CI -33·21 to -14·34) and PFNA (-13·00%, -21·87 to -3·12) in adolescents, and PFOA (-12·45%, -17·28 to -7·35), PFOS (-25·30%, -29·67 to -20·65), PFNA (-21·65%, -26·19 to -16·82), and PFHxS (-11·70%, -17·32 to 5·70) in adults. Associations for serum folate concentrations and PFAS were in line with those found for red blood cell folate levels, although the magnitude of the effects was lower. Restricted cubic spline models suggested linearity of the observed associations, particularly for associations in adults.

INTERPRETATION

In this large-scale, nationally representative study, we found consistent inverse associations for most examined serum PFAS compounds in relation to folate concentrations measured in either red blood cells or serum among both adolescents and adults. These findings are supported by mechanistic in-vitro studies that show the potential of PFAS to compete with folate for several transporters implicated in PFAS toxicokinetics. If confirmed in experimental settings, these findings could have important implications for interventions to reduce the accumulated PFAS body burden and mitigate the related adverse health effects.

FUNDING

United States National Institute of Environmental Health Sciences.

Re-evaluation of the risks to public health related to the presence of bisphenol A (BPA) in foodstuffs

In 2015, EFSA established a temporary tolerable daily intake (t-TDI) for BPA of 4 μg/kg body weight (bw) per day. In 2016, the European Commission mandated EFSA to re-evaluate the risks to public health from the presence of BPA in foodstuffs and to establish a tolerable daily intake (TDI). For this re-evaluation, a pre-established protocol was used that had undergone public consultation. The CEP Panel concluded that it is Unlikely to Very Unlikely that BPA presents a genotoxic hazard through a direct mechanism. Taking into consideration the evidence from animal data and support from human observational studies, the immune system was identified as most sensitive to BPA exposure. An effect on Th17 cells in mice was identified as the critical effect; these cells are pivotal in cellular immune mechanisms and involved in the development of inflammatory conditions, including autoimmunity and lung inflammation. A reference point (RP) of 8.2 ng/kg bw per day, expressed as human equivalent dose, was identified for the critical effect. Uncertainty analysis assessed a probability of 57-73% that the lowest estimated Benchmark Dose (BMD) for other health effects was below the RP based on Th17 cells. In view of this, the CEP Panel judged that an additional uncertainty factor (UF) of 2 was needed for establishing the TDI. Applying an overall UF of 50 to the RP, a TDI of 0.2 ng BPA/kg bw per day was established. Comparison of this TDI with the dietary exposure estimates from the 2015 EFSA opinion showed that both the mean and the 95th percentile dietary exposures in all age groups exceeded the TDI by two to three orders of magnitude. Even considering the uncertainty in the exposure assessment, the exceedance being so large, the CEP Panel concluded that there is a health concern from dietary BPA exposure.

Nutrition, female fertility and in vitro fertilization outcomes

The investigation of modifiable factors that may exert influences on female reproductive health and in vitro fertilization (IVF) outcomes is increasing. Growing attention is being paid to nutrition. The aim of the present review is to recapitulate the current understanding on the effects of nutrition on female fertility and IVF outcomes. In particular, the three main classes of macromolecules have been analysed i.e. carbohydrates, proteins and fatty acids. An increasing number of studies have focused on the potential benefit of whole grain, vegetables and omega-3 polynsatured fatty acids (ω-3 PUFAs) on reproductive outcomes. Controversial results exist regarding the consumption of omega-6 (ω-6) PUFAs and dairy. Overall, nutrition appears to represent a modifiable factor that may play a significant role in the context of female reproduction and IVF outcomes, but the limited number of studies and the discrepancies between the available data call for further research in the area.

Red Blood Cell Folate Modifies the Association between Serum Per- and Polyfluoroalkyl Substances and Antibody Concentrations in U.S. Adolescents

Per- and polyfluoroalkyl substances (PFAS) exposure has been associated with reduced antibody levels. Higher red blood cell (RBC) folate was previously associated with lower serum PFAS concentrations in adolescents. This study included 819 adolescents aged 12-19 years who had detectable rubella and measles antibody levels in serum from the U.S. National Health and Nutrition Examination Survey 2003-2004 and 2009-2010 cycles. We found inverse associations between serum PFOS and PFHxS and rubella antibodies, between PFOA and mumps antibodies, and between PFAS mixtures and rubella and mumps antibodies, only among adolescents with RBC folate concentrations <66th percentile (lower folate group) while not among adolescents with higher RBC folate levels (upper folate group). Specifically, per quartile increase in serum concentrations of the total PFAS mixture was associated with a 9.84% (95% CI: -15.57%, -3.74%) decrease in rubella antibody and an 8.79% (95% CI: -14.39%, -2.82%) decrease in the mumps antibody concentrations only in the lower folate group, while null associations were found for the upper folate group. If confirmed in mechanistic studies or prospective epidemiologic studies, these findings may have important implications for using folate as a mitigation measure against immune-related PFAS effects.

The Placental Function Beyond Pregnancy: Insights from Latin America

Currently, more than 100,000 papers had been published studying the placenta in both physiological and pathological contexts. However, relevant health conditions affecting placental function, mostly found in low-income countries, should be evaluated deeper. This review will raise some - of what we think necessary - points of discussion regarding challenging topics not fully understood, including the paternal versus maternal contribution on placental genes imprinting, placenta-brain communication, and some environmental conditions affecting the placenta. The discussions are parts of an international effort to fulfil some gaps observed in this area, and Latin-American research groups currently evaluate that.

Self-reported history of comorbidities and markers of ovarian reserve among subfertile women

PURPOSE

To investigate whether history of comorbidities is associated with markers of ovarian reserve among subfertile women.

METHODS

This observational study includes 645 women seeking fertility care at the Massachusetts General Hospital who enrolled in the Environment and Reproductive Health (EARTH) study (2005-2019). Women completed a comprehensive questionnaire including medical diagnosis of comorbidities. Ovarian reserve markers including antral follicle count (AFC), assessed by transvaginal ultrasound, and circulating serum levels of day 3 FSH and AMH, are assessed by immunoassays. We fit linear regression models to evaluate the association between history of comorbidities and markers of ovarian reserve while adjusting for confounders.

RESULTS

Self-reported history of hypertension, cancer, and neurological disorders was negatively associated with AFC in unadjusted models and in adjusted models for age, smoking, physical activity, comorbidity count, and BMI. Adjusted mean AFC (95% CI) was lower among women with history of hypertension, compared to women with no self-reported history of hypertension (11.5 vs 15.6, p value 0.0001). In contrast, day 3 FSH levels were positively related to history of eating disorders in both unadjusted and adjusted models (10.8 vs. 7.43 IU/L, p value ≤ 0.0001). Self-reported history of other comorbidities was unrelated to AFC, day 3 FSH, and AMH levels.

CONCLUSIONS

History of hypertension, cancer, and neurological disorders was negatively associated with AFC, and eating disorders were positively related to day 3 FSH levels. The prevention of common comorbidities among women in reproductive age may help increase women's fertility given the declining birth rates and increasing use of assisted reproductive technologies in the past years.

Pregnancy urinary concentrations of bisphenol A, parabens and other phenols in relation to serum levels of lipid biomarkers: Results from the EARTH study

The epidemiologic literature on associations between urinary phenol concentrations and lipid profiles during pregnancy is limited. We examined whether urinary concentrations of phenol and phenol replacement biomarkers were associated with serum lipid levels among pregnant women. This cross-sectional study included 175 women attending the Massachusetts General Hospital Fertility Center who enrolled in the Environment and Reproductive Health (EARTH) Study between 2005 and 2017 and had data available on urinary phenol biomarkers and serum lipids during pregnancy. We used linear regression models to assess the relationship between groups of urinary phenol and phenol replacement biomarkers and serum lipid levels [total cholesterol, high density lipoprotein (HDL), non-HDL, low-density lipoprotein (LDL) cholesterol, and triglycerides], while adjusting for age at sample collection, pre-pregnancy BMI, education, race, infertility diagnosis, cycle type, number of fetuses, trimester and specific gravity. In adjusted models, pregnant women with urinary propylparaben concentrations in the highest tertile had 10% [22 (95% CI = 5, 40) mg/dL], 12% [19 (95% CI = 2, 36) mg/dL] and 16% [19 (95% CI = 3, 35) mg/dL] higher mean total, non-HDL and LDL cholesterol, respectively, compared to women with concentrations in the lowest tertile. Similar elevations were observed for urinary bisphenol A concentrations. Urinary bisphenol S, benzophenone-3, triclosan, methylparaben, ethylparaben, and butylparaben were unrelated to serum lipids. Among pregnant women, urinary concentrations of bisphenol A and propylparaben were associated with higher serum levels of total, non-HDL and LDL cholesterol.

Beverage intake and ovarian reserve among women from a fertility center

OBJECTIVE

To evaluate the associations of caffeinated, alcoholic, and sweetened beverage intakes with antral follicle count (AFC), a well-accepted biomarker of ovarian reserve.

DESIGN

Observational prospective cohort study.

SETTING

Fertility center at an academic hospital.

PATIENTS

This study includes 567 women seeking fertility care at the Massachusetts General Hospital who participated in the Environment and Reproductive Health Study.

INTERVENTION

None. Women self-reported consumption of caffeinated (coffee, tea, soda), alcoholic (wine, beer, liquor), sugar-sweetened, and artificially sweetened beverages using a validated food-frequency questionnaire.

MAIN OUTCOME MEASURE

Antral follicle count was assessed using a transvaginal ultrasound performed on the 3rd day of an unstimulated menstrual cycle or on the 3rd day of a progesterone withdrawal bleed.

RESULTS

Median (interquartile range) age and AFC were 35.0 (32.0-38.0) years and 13.0 (9.0-18.0), respectively. Median (range) intake of caffeinated, alcoholic, sugar-sweetened, and artificially sweetened beverages in servings/day were 1.08 (0-7.08), 0.35 (0-3.84), 0.04 (0-4.80), and 0.04 (0-7.50), respectively. All examined beverages were unrelated to AFC. The multivariable adjusted mean AFC (95% confidence interval) for women in the top and bottom quartiles of intake were 13.8 (13.0-14.7) and 13.8 (12.9-14.7) for caffeinated beverages; 13.8 (13.0-14.7) and 13.8 (13.0-14.6) for alcoholic beverages; 13.5 (12.6-14.4) and 13.3 (12.4-14.2) for sugar-sweetened beverages; and 13.2 (12.4-14.1) and 13.4 (12.6-14.3) for artificially sweetened beverages.

CONCLUSION

Low-to-moderate intakes of caffeinated, alcoholic, sugar-sweetened, and artificially sweetened beverages were unrelated to ovarian reserve, as measured by AFC, in a cohort of women seeking fertility care.

Does Older Age Modify Associations between Endocrine Disrupting Chemicals and Fecundability?

Urinary concentrations of several endocrine disrupting chemicals, including phthalate metabolites, bisphenol A (BPA), and benzophenone (BP)-type ultraviolet (UV) filters, have been associated with a longer time-to-pregnancy (TTP). Potential modification of these associations by couple’s age has not been studied. TTP was defined as the number of prospectively observed menstrual cycles a couple attempted pregnancy until the occurrence of a human chorionic gonadotropic-detected pregnancy. Urinary concentrations of two BP-type UV filters and three phthalate metabolites were measured at baseline. Fecundability odds ratios (FORs) and 95% confidence intervals (CIs) were estimated for each chemical adjusting for age, body mass index, serum cotinine, creatinine, and accounting for right censoring and left truncation. Models evaluated effect modification between EDC concentrations and TTP by partner’s age, dichotomized at 35 years. Separate models were run for male and female partners. No significant effect modification was observed for any EDC for either partner, but data were suggestive of a longer TTP among females aged ≥35 years, particularly for BP-2 (FOR = 0.61, 95% CI 0.36, 1.05) and 4-hydroxybenzophenone (FOR = 0.71, 95% CI: 0.46, 1.09) reflecting 39% and 29% reductions in fecundability, respectively. We saw no evidence of effect modification by couples’ age on associations between TTP and urinary phthalate or BPA metabolite concentrations. Across the EDCs we examined, we found little evidence that age modifies TTP-exposure associations.

Association of Urinary Phthalate and Phthalate Replacement Metabolite Concentrations with Serum Lipid Biomarker Levels among Pregnant Women Attending a Fertility Center

We examined whether urinary concentrations of phthalate and phthalate replacement metabolites were associated with lipid biomarker levels among pregnant women. This cross-sectional study included 175 women who enrolled in the Environment and Reproductive Health (EARTH) Study (2005–2017). We used linear regression models to assess the relationship between urinary phthalates and lipid biomarkers [triglycerides, total cholesterol, high density lipoprotein (HDL), non-HDL, and low-density lipoprotein (LDL) cholesterol] levels while adjusting for confounders. Pregnant women in the highest quartile of urinary mono(2-ethyl-5-carboxypentyl) phthalate (MECPP) had, overall, 14% [31 (95% CI = 6.56) mg/dL], 21% [33 (95% CI = 9.57) mg/dL] and 25% [30 (95% CI = 8.53) mg/dL] higher serum total, non-HDL and LDL cholesterol, respectively, compared to women in the lowest quartile of MECPP. Similar positive associations were found for urinary concentrations of other metabolites of di(2-ethylhexyl) phthalate, mono(2-ethylhexyl) phthalate, and mono(2-ethyl-5-oxohexyl) phthalate. Pregnant women with urinary mono-n-butyl phthalate (MBP) in the highest quartile had higher triglycerides and non-HDL cholesterol compared to women with MBP in the lowest quartile. Women with detectable concentrations of two phthalate replacement metabolites had lower HDL cholesterol compared to women with non-detectable concentrations. Gestational urinary concentrations of certain phthalate and phthalate replacement metabolites were associated with lipid levels among these women.

Paternal adherence to healthy dietary patterns in relation to sperm parameters and outcomes of assisted reproductive technologies

OBJECTIVE

To investigate whether men's adherence to dietary patterns promoted for the prevention of cardiovascular disease is associated with semen parameters and couples' assisted reproductive technology (ART) outcomes.

DESIGN

Prospective cohort study.

SETTING

Fertility center at an academic medical center.

PATIENT(S)

A total of 245 men and their female partners who underwent 438 ART cycles between 2007 and 2020.

INTERVENTION(S)

Male pretreatment dietary intake was assessed with a 131-item food frequency questionnaire from which we calculated eight a priori defined scores: Trichopoulou Mediterranean, Alternate Mediterranean, Panagiotakos Mediterranean, Healthy Eating Index, Alternative Healthy Eating Index, American Heart Association, Dietary Approaches to Stop Hypertension, and Plant-based.

MAIN OUTCOME MEASURE(S)

The primary outcome was live births per treatment cycle. The secondary outcomes were fertilization, implantation, and clinical pregnancy and seminogram parameters.

RESULT(S)

There was an inverse association between greater adherence by men to the Panagiotakos Mediterranean diet and the American Heart Association dietary pattern and lower fertilization rate. However, there were no significant associations between men's adherence to any of the analyzed dietary patterns and the probabilities of implantation, clinical pregnancy, or live birth in multivariable-adjusted models. No significant differences in any of the semen parameters were found between participants of the lowest quartile and those of the highest quartile of the eight dietary patterns.

CONCLUSION(S)

These findings suggest that men's adherence to several a priori defined dietary scores with documented cardiovascular benefits is not related to major outcomes of infertility treatment with ART or semen quality.

Urinary phthalate metabolite concentrations are negatively associated with follicular fluid anti-müllerian hormone concentrations in women undergoing fertility treatment

Exposure to phthalates, endocrine-disrupting chemicals commonly used as plasticizers and in consumer products, has been associated with infertility and premature ovarian failure. Our objective was to investigate whether urinary phthalate metabolite concentrations were associated with pre-ovulatory follicular fluid (FF) anti-müllerian hormone (AMH) concentrations in women undergoing fertility treatment. This cross-sectional analysis included 138 women with urinary phthalate data available in the Environment and Reproductive Health (EARTH) Study (2010-2016) in whom FF AMH concentrations were quantified using a sandwich enzyme-linked immunosorbent assay (ELISA). We also quantified 8 phthalate metabolite concentrations using tandem mass spectrometry in 1-2 urine samples per cycle (total 331 urines) and calculated the cycle-specific geometric mean for each metabolite. We applied cluster-weighted generalized estimating equation models (CWGEE) to evaluate the associations of tertiles of urinary phthalate metabolite concentrations with log-transformed FF AMH concentrations adjusting for potential confounders. Study participants had median age of 34.0 years (IQR 32.0, 37.0), 83% were white, and median BMI of 23.1 kg/m² (IQR 21.2, 26.1). The following stimulation protocols were used: luteal phase agonist (70%), antagonist (14%), or flare (16%). Urinary concentrations of select phthalate metabolites were negatively associated with FF AMH. For example, women whose urinary mEOHP was in the lowest tertile (range 0.30-4.04 ng/ml) had an adjusted mean FF AMH of 0.72 ng/mL (95% CI = 0.36, 1.44), compared to women in the highest tertile (range 9.90-235), who had an adjusted mean of 0.24 ng/mL (95% CI = 0.12-0.48, p < 0.05). The negative association between urinary concentrations of certain phthalate metabolites with FF AMH concentrations may have implications for antral follicle recruitment and fertility treatment outcomes.

Hair mercury levels, intake of omega-3 fatty acids and ovarian reserve among women attending a fertility center

OBJECTIVE

To investigate the association of hair mercury (Hg) levels with antral follicle count (AFC), as a marker of ovarian reserve, and evaluate whether this relationship differed among women with high vs. low total intake of long chain omega-3 polyunsaturated fatty acids (n3PUFA) from foods and supplements.

DESIGN

We included 353 women attending an academic fertility center (2007-2019) who had data on hair Hg levels, total n3PUFA intake, and AFC.

METHODS

Hair Hg levels were assessed using a Direct Mercury Analyser, total n3PUFA intake was estimated using an extensively validated food frequency questionnaire, and AFC was assessed by transvaginal ultrasonography. Poisson regression models adjusted for potential confounders were used to evaluate the association of hair Hg levels (divided into tertiles, and as above vs below EPA reference (1 ppm)) with AFC. Associations were also evaluated after stratification by median n3PUFA intake (≤0.124% vs. >0.125% calories/week).

RESULTS

Women's median hair Hg level was 0.60 ppm (range = 0.001-8.60 ppm), with more than 30% > 1 ppm (EPA reference level). Hair Hg was positively related to AFC after adjusting for age, BMI, smoking status, infertility diagnosis, and alcohol intake. However, associations became attenuated after adjustment for intake of total n3PUFA. The positive associations of hair Hg and AFC were observed only among women above the median total n3PUFA intake. Specifically, women who consumed >0.125% calories/week of total n3PUFA had mean AFCs of 11.9, 13.2 and 14.1, respectively, across increasing tertiles of hair Hg (p,trend = 0.004). Similar results were found when hair Hg was divided above vs below EPA reference (mean AFC = 12.7 vs. 14.1, p = 0.008).

CONCLUSIONS

In these women, positive associations of hair Hg with AFC may be reflective of beneficial effects of n3PUFA on ovarian reserve rather than a beneficial effect of Hg per se. Our findings highlight the importance of considering diet when exploring Hg effects on women's reproductive health in urban settings.

The effect of plastic bottled water consumption on outcomes of ICSI cycles undertaken for unexplained infertility

RESEARCH QUESTION

Do bisphenol A (BPA) levels in maternal urine, serum and follicular fluid affect embryo quality and intracytoplasmic sperm hinjection (ICSI) cycle outcomes in women with unexplained infertility?

DESIGN

Prospective study conducted between 1 April 2019 and 30 September 2019. The study cohort consisted of 82 women aged between 23 and 33 years who underwent intracytoplasmic sperm injection owing to unexplained infertility and provided urine, blood and follicular fluid samples on the day of oocyte retrieval. Consumption of drinking water from plastic carboys or bottles at home were considered as chronic BPA exposure. Demographic features and IVF outcomes of the patients were collected.

RESULTS

Among the 82 women with unexplained infertility, clinical pregnancy was achieved in 22 (26.8%) patients after the IVF and embryo transfer cycle. The patients who consumed tap water had statistically significantly lower BPA values in three body fluids compared with patients who consumed plastic bottled water (all P < 0.001). Women who had grade 1 embryos transferred had lower serum BPA values than women who had grade 2 embryos transferred (10.8 ± 5.2 versus 26.9 ± 22 ng/ml, P = 0.003). Serum and follicular fluid BPA levels were statistically significantly higher in women who failed to achieve clinical pregnancy (P < 0.001, P = 0.006, respectively) and obtain a live birth (both P = 0.007).

CONCLUSIONS

A negative relationship was found between serum and follicular fluid BPA levels and embryo quality, clinical pregnancy and live birth in these women. In addition, the BPA levels of women who consume tap water at home were lower than those who use plastic bottled water.

Paternal mixtures of urinary concentrations of phthalate metabolites, bisphenol A and parabens in relation to pregnancy outcomes among couples attending a fertility center

BACKGROUND

Few epidemiologic studies have evaluated the impact of paternal environmental exposures, particularly as mixtures, on couples' pregnancy outcomes.

OBJECTIVE

We investigated whether mixtures of paternal urinary bisphenol A (BPA), paraben, and phthalates were associated with pregnancy outcomes among couples attending a fertility center.

METHODS

We included 210 couples undergoing 300 in vitro fertilization (IVF) between 2004 and 2017 in this prospective analysis. We quantified paternal urinary biomarker concentrations in one sample per cycle using isotope-dilution tandem mass spectrometry. We used principal component analysis (PCA) to identify correlations of biomarker concentrations and multivariable Cox proportional hazards models for discrete survival time to estimate the hazard ratios (HRs) and 95% CIs for the associations between PCA-derived factor scores and probability of failing to achieve a live birth. Interactions were also included in the models to examine strength of associations over three vulnerable periods [embryo transfer to implantation, implantation to clinical pregnancy, and clinical pregnancy to live birth]. Models were adjusted for paternal and maternal ages and body mass indexes, urinary dilution (specific gravity) and year of collection, infertility diagnosis, and other PCA factor scores. Sensitivity analyses with further adjustment for maternal PCA factor scores were performed.

RESULTS

We identified three factors, representing di-2-ethylhexyl phthalate (DEHP) metabolites, BPA and non-DEHP metabolites, and parabens, accounting for 56%, 15% and 10%, respectively, of the total variance explained. An interquartile range (25th and 75th percentiles) increase in the DEHP-related factor score was associated with elevated probability of failing prior to live birth (HR = 1.41, 95% CI: 1.08, 1.81) and the association was stronger between implantation and clinical pregnancy as well as between clinical pregnancy and live birth compared to before implantation. The overall HRs of failure for the BPA/non-DEHP-related and paraben-related factor scores were HR = 1.24 (95% CI: 0.97, 1.59) and HR = 0.99 (95% CI: 0.80, 1.24). We found similar HRs when additionally adjusting for maternal PCA factor scores.

CONCLUSION

Paternal mixtures of urinary concentrations of DEHP metabolites were related to higher infertility treatment failure.

Relationship between nutrition and reproduction

BACKGROUND

Recently, the relationship between nutrition and reproduction is being studied. In particular, when older women receive reproductive treatment, egg aging causes greater problems than organic factors.

METHODS

This study investigated the relationship between nutrition and reproduction with a focus on factors that cause aging, including oxidation, glycation, and chronic inflammation. A large volume of data concerning each nutrient's relationship with reproductive medicine was collected from a number of observational studies.

MAIN FINDINGS

The results showed that refined carbohydrates should be avoided and care should be taken to achieve proper intake of omega-3 fatty acids. Folic acid and vitamin D were also effective. For men, antioxidant measures are especially effective. The effects of antioxidants are related to insulin resistance, which causes chronic inflammation.

CONCLUSION

Recent research has shown that rather than meal content, meal intervals are more important for improving insulin resistance. Future research should examine lifestyle-related nutrition factors and their relationships to reproductive treatment.

Emerging Trends in Research on Food Compounds and Women’s Fertility: A Systematic Review

Pro-healthy behaviours, including the diet, are significant factors in maintaining women’s fertility health. However, to improve the patient’s nutrition management, it is important to seek food-derived bioactive compounds to support fertility treatment. This review analysed recent studies of food compounds related to fertility, using databases including PubMed, Web of Science and Science Direct as well as PRISMA (preferred reporting items for systematic reviews) to ensure complete and transparent reporting of systematic reviews. This review lists foods associated with a higher birth rate, using original papers from the last five years (2015). The analysis included the impact of food compounds such as caffeine, fatty acids, folates and vitamin D, as well as the intake of fish, whole grains, dairy and soya. In addition, dietary patterns and total diet composition supporting women’s fertility were also analysed. The results will encourage further research on the relationship between food components and fertility.

Urinary Concentrations of Phthalate Metabolite Mixtures in Relation to Serum Biomarkers of Thyroid Function and Autoimmunity among Women from a Fertility Center

BACKGROUND

Although previous epidemiological studies have explored associations of phthalate metabolites with thyroid function, no studies to date have assessed associations of mixtures with thyroid function and autoimmunity among potentially susceptible subgroups such as subfertile women.

OBJECTIVE

We aimed to explore associations of mixtures of urinary phthalate metabolites with serum markers of thyroid function and autoimmunity.

METHODS

This cross-sectional study included 558 women attending a fertility center who provided one spot urine and one blood sample at enrollment (2005-2015). We quantified urinary concentrations of eight phthalate metabolites using mass spectrometry, and biomarkers of thyroid function [thyroid-stimulating hormone (TSH), free and total thyroxine (fT4, TT4) and triiodothyronine (fT3, TT3), and autoimmunity [thyroid peroxidase and thyroglobulin antibodies (TPOAb and TgAb, respectively)] in serum using electrochemiluminescence assays. We applied principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) to identify the main patterns of urinary phthalate metabolites. We used linear mixed models to assess the association between PCA-derived factor scores in quintiles and serum thyroid function and autoimmunity, adjusting for age, body mass index (BMI), specific gravity (SG), and, for the PCA, other factor scores.

RESULTS

We observed two factors using PCA, one representing the di(2-ethylhexyl) (DEHP) and another non-DEHP metabolites. Compared to women in the lowest quintile of the DEHP factor scores, women in the highest quintile had significantly lower serum concentrations of fT4, TT4, fT3, and TT3 [absolute difference: -0.62; 95% confidence interval (CI): -0.12, -0.01; p=0.04; absolute difference: -8.31; 95% CI: -13.8, -2.85; p=0.003; absolute difference: -0.37; 95% CI: 0.54, -0.19; p<0.0001; and absolute difference: -0.21; 95% CI: -0.32, -0.10; p=0.003, respectively]. Using BKMR, we observed that mono(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) was the primary contributor to these negative associations. DEHP and non-DEHP factor scores were not associated with serum TSH, TgAb, or TPOAb.

CONCLUSIONS

Mixtures of urinary DEHP metabolites were inversely associated with serum biomarkers of thyroid function but not with autoimmunity, which were within normal ranges for healthy adult women. https://doi.org/10.1289/EHP6740.

Supplemental Folate and the Relationship Between Traffic-Related Air Pollution and Livebirth Among Women Undergoing Assisted Reproduction

Traffic-related air pollution has been linked to higher risks of infertility and miscarriage. We evaluated whether folate intake modified the relationship between air pollution and livebirth among women using assisted reproductive technology (ART). Our study included 304 women (513 cycles) presenting to a fertility center in Boston, Massachusetts (2005-2015). Diet and supplements were assessed by food frequency questionnaire. Spatiotemporal models estimated residence-based daily nitrogen dioxide (NO2), ozone, fine particulate, and black carbon concentrations in the 3 months before ART. We used generalized linear mixed models with interaction terms to evaluate whether the associations between air pollutants and livebirth were modified by folate intake, adjusting for age, body mass index, race, smoking, education, infertility diagnosis, and ART cycle year. Supplemental folate intake significantly modified the association of NO2 exposure and livebirth (P = 0.01). Among women with supplemental folate intakes of <800 μg/day, the odds of livebirth were 24% (95% confidence interval: 2, 42) lower for every 20-parts-per-billion increase in NO2 exposure. There was no association among women with intakes of ≥800 μg/day. There was no effect modification of folate on the associations between other air pollutants and livebirth. High supplemental folate intake might protect against the adverse reproductive consequences of traffic-related air pollution.

Invited Commentary: Interaction Between Diet and Chemical Exposures

A growing literature indicates that changes in modifiable factors, including diet, can counteract the toxic developmental and reproductive health effects of chemical exposures. In this issue of the Journal, Gaskins et al. (Am J Epidemiol. 2019;000(000):000-000) present data supporting this hypothesis. Specifically, using data on a cohort of 304 women seeking fertility treatment in Boston, Massachusetts, they found that women with higher exposure to ambient air pollutants had lower fertility treatment success but only when they also consumed <800 μg/day of supplemental folate. No association was observed among women consuming ≥800 μg/day of supplemental folate. The public health importance of this interaction is high: Diet and dietary supplement intake are modifiable factors, whereas exposure to air pollution is less so. While this research question is grounded in a strong biological hypothesis related to epigenetic modifications, oxidative stress, and inflammation, this study raises several key questions. In this commentary, we discuss the inconsistency of the interaction across exposure metrics, the possibility of unmeasured confounding by folate intake, and the importance of examining this association in populations with lower folate intake and/or higher exposure to air pollution.

Urinary concentrations of benzophenone-3 and reproductive outcomes among women undergoing infertility treatment with assisted reproductive technologies

Benzophenone-3 is used in a variety of cosmetic products as a sunscreen, and has shown weak estrogenic and antiandrogenic activity in animal and in vitro studies. Few studies have evaluated whether benzophenone-3 is associated with reproductive outcomes among women. We studied 304 women undergoing infertility treatment (2007-2017) in the prospective Environment and Reproductive Health cohort study and who underwent 449 treatment cycles (n = 788 urines). Generalized linear mixed models were used with random intercepts to account for multiple cycles, and adjusting for confounders including physical activity. Analyses were also stratified by self-reported moderate/heavy outdoor work. The cycle-specific median (IQR) urinary benzophenone-3 concentration was 147 (58, 462) μg/L, and 98% samples had detectable concentrations. Self-reported sunscreen use, physical activity, and time spent on moderate/heavy outdoor work were positively associated with urinary benzophenone-3. Adjusted probabilities of implantation, clinical pregnancy and live birth were higher in increasing quartiles of benzophenone-3, but these associations were restricted to women who reported spending time outdoors performing moderate/heavy work. Specifically, among these women, those in the highest quartile of benzophenone-3 concentrations had 51% higher implantation (p,trend = 0.02), 68% higher clinical pregnancy (p,trend = 0.01) and 75% higher live birth (p,trend = 0.02) adjusted probabilities than women in the lowest quartile. Benzophenone-3 was unrelated to these outcomes among women who did not report doing moderate/heavy work outdoors. These results confirm that sunscreen use is a source of benzophenone-3 exposure, and show positive associations between benzophenone-3 and pregnancy outcomes, especially among women who reported engaging in outdoor work. Since these associations may be subject to important residual confounding by lifestyle factors, further research is needed to confirm these novel results in other populations, and to investigate whether other factors may be affecting the relation of benzophenone-3 with fertility and other health outcomes.

Urinary concentrations of bisphenol A, parabens and phthalate metabolite mixtures in relation to reproductive success among women undergoing in vitro fertilization

BACKGROUND

We have previously investigated whether urinary concentrations of bisphenol A (BPA), parabens, and phthalate metabolites were individually associated with reproductive outcomes among women undergoing in vitro fertilization (IVF) treatment. However, humans are typically exposed to many man-made chemicals simultaneously. Thus, investigating one chemical at a time may not represent the effect of mixtures.

OBJECTIVE

To investigate whether urinary concentrations of BPA, parabens, and phthalate metabolite mixtures are associated with reproductive outcomes among women undergoing IVF.

METHODS

This prospective cohort study included 420 women contributing 648 IVF cycles who provided up to two urine samples per cycle prior to oocyte retrieval (N = 1145) between 2006 and 2017 at the Massachusetts General Hospital Fertility Center, and had available urine biomarker data. Urinary concentrations of BPA, parabens, and phthalate metabolites were quantified using isotope-dilution tandem mass spectrometry. Intermediate and clinical end-points of IVF treatments were abstracted from electronic medical records. Principal component analysis (PCA) and Bayesian kernel machine regression (BKMR) were used to identify main patterns of BPA, parabens, and phthalate metabolites concentrations. We used generalized linear mixed models to evaluate the association between PCA-derived factor scores, in quartiles, and IVF outcomes, using random intercepts to account for multiple IVF cycles and adjusting for known confounders. Because of temporal trends in exposure, we conducted a sensitivity analysis restricted to women who underwent IVF cycles in the earlier years of study (2006-2012).

RESULTS

Urinary concentrations of BPA, parabens, and most phthalate metabolites were significantly lower during the second half of the study period (2013-2017) than during the first half (2006-2012). None of the three factors derived from the PCA [di(2-ethylhexyl) phthalate (DEHP), non-DEHP, and paraben] was associated with IVF outcomes in the main analyses. Similarly, BKRM analyses did not identify any associations of individual urinary concentrations of BPA, paraben and phthalate metabolites with IVF outcomes while accounting for correlation between exposures. However, in sensitivity analyses restricted to women who underwent IVF cycles from 2006 to 2012, where concentrations of most phthalates and phenols were higher, there were decreases in implantation, clinical pregnancy, and live birth across quartiles of the DEHP factor. Specifically, women in the highest quartile of the DEHP factor had, on average, lower probabilities of implantation (-22% p, trend = 0.08), clinical pregnancy (-24% p, trend = 0.14), and live birth (-38% p, trend = 0.06) compared to women in the lowest quartile. Among this group of women, BKMR results did not identify any single contributor driving the decreased probabilities of live birth within the DEHP factor.

CONCLUSIONS

We confirmed that women undergoing IVF are concurrently exposed to multiple endocrine disrupting chemicals (EDCs). While we found no overall significant associations, we observed diminished pregnancy success with specific clusters of chemicals among women who underwent IVF cycles in earlier years of study, when urinary concentrations of these EDCs were higher.

Diet and female fertility: doctor, what should I eat?

Fecundity is the capacity to produce offspring. Identifying dietary factors that influence human fecundity is of major clinical and public health significance. This review focuses on the evidence from epidemiologic literature for the relationships between key nutritional factors and female reproductive potential. According to existing data, women trying to achieve pregnancy are encouraged to increase consumption of whole grains, omega-3 fatty acids, fish, and soy and to reduce consumption of trans fats and red meat. In addition, a daily multivitamin that contains folic acid before and during pregnancy may not only prevent birth defects, but also improve the chance of achieving and maintaining a pregnancy. In contrast, there is limited evidence supporting an association between vitamin D and human fecundity outcomes despite promising evidence from nonhuman studies. Questions for future research included the roles of other types of fat (especially omega-6 and monounsaturated fats) and protein (especially white meat and seafood) on female fertility; particular attention should also be paid to exposure to environmental contaminants in foods. Although much work remains, this review accrued best available evidence to provide practical dietary recommendations for women trying to conceive.

One-Carbon Metabolism: Linking Nutritional Biochemistry to Epigenetic Programming of Long-Term Development

One-carbon (1C) metabolism comprises a series of interlinking metabolic pathways that include the methionine and folate cycles that are central to cellular function, providing 1C units (methyl groups) for the synthesis of DNA, polyamines, amino acids, creatine, and phospholipids. S-adenosylmethionine is a potent aminopropyl and methyl donor within these cycles and serves as the principal substrate for methylation of DNA, associated proteins, and RNA. We propose that 1C metabolism functions as a key biochemical conduit between parental environment and epigenetic regulation of early development and that interindividual and ethnic variability in epigenetic-gene regulation arises because of genetic variants within 1C genes, associated epigenetic regulators, and differentially methylated target DNA sequences. We present evidence to support these propositions, drawing upon studies undertaken in humans and animals. We conclude that future studies should assess the epigenetic effects of cumulative (multigenerational) dietary imbalances contemporaneously in both parents, as this better represents the human experience.

Interventions to Address Environmental Metabolism-Disrupting Chemicals: Changing the Narrative to Empower Action to Restore Metabolic Health

Metabolic disease rates have increased dramatically over the last four decades. Classic understanding of metabolic physiology has attributed these global trends to decreased physical activity and caloric excess; however, these traditional risk factors insufficiently explain the magnitude and rapidity of metabolic health deterioration. Recently, the novel contribution of environmental metabolism-disrupting chemicals (MDCs) to various metabolic diseases (including obesity, diabetes, and non-alcoholic fatty liver disease) is becoming recognized. As this burgeoning body of evidence has matured, various organic and inorganic pollutants of human and natural origin have emerged as metabolic disease risk factors based on population-level and experimental data. Recognition of these heretofore underappreciated metabolic stressors now mandates that efforts to mitigate the devastating consequences of metabolic disease include dedicated efforts to address environmental drivers of disease risk; however, there have not been adequate recommendations to reduce exposures or to mitigate the effects of exposures on disease outcomes. To address this knowledge gap and advance the clinical translation of MDC science, herein discussed are behaviors that increase exposures to MDCs, interventional studies to reduce those exposures, and small-scale clinical trials to reduce the body burden of MDCs. Also, we discuss evidence from cell-based and animal studies that provide insights into MDC mechanisms of action, the influence of modifiable dietary factors on MDC toxicity, and factors that modulate MDC transplacental carriage as well as their impact on metabolic homeostasis. A particular emphasis of this discussion is on critical developmental windows during which short-term MDC exposure can elicit long-term disruptions in metabolic health with potential inter- and transgenerational effects. While data gaps remain and further studies are needed, the current state of evidence regarding interventions to address MDC exposures illuminates approaches to address environmental drivers of metabolic disease risk. It is now incumbent on clinicians and public health agencies to incorporate this knowledge into comprehensive strategies to address the metabolic disease pandemic.

First Trimester Urinary Bisphenol and Phthalate Concentrations and Time to Pregnancy: A Population-Based Cohort Analysis

BACKGROUND

Increasing evidence suggests that exposure to synthetic chemicals such as bisphenols and phthalates can influence fecundability. The current study describes associations of first trimester urinary concentrations of bisphenol A (BPA), BPA analogs, and phthalate metabolites with time to pregnancy (TTP).

METHODS

Among 877 participants in the population-based Generation R pregnancy cohort, we measured first trimester urinary concentrations of bisphenols and phthalates [median gestational age, 12.9 weeks (interquartile range, 12.1, 14.4)]. We used fitted covariate-adjusted Cox proportional hazard models to examine associations of bisphenol and phthalate concentrations with TTP. Participants who conceived using infertility treatment were censored at 12 months. Biologically plausible effect measure modification by folic acid supplement use was tested.

RESULTS

In the main models, bisphenol and phthalate compounds were not associated with fecundability. In stratified models, total bisphenols and phthalic acid were associated with longer TTP among women who did not use folic acid supplements preconceptionally [respective fecundability ratios per each natural log increase were 0.90 (95% CI, 0.81 to 1.00) and 0.88 (95% CI, 0.79 to 0.99)]. Using an interaction term for the exposure and folic acid supplement use showed additional effect measure modification by folic acid supplement use for high-molecular-weight phthalate metabolites.

CONCLUSIONS

We found no associations of bisphenols and phthalates with fecundability. Preconception folic acid supplementation seems to modify effects of bisphenols and phthalates on fecundability. Folic acid supplements may protect against reduced fecundability among women exposed to these chemicals. Further studies are needed to replicate these findings and investigate potential mechanisms.

Female exposure to endocrine disrupting chemicals and fecundity: a review

PURPOSE OF REVIEW

Endocrine disrupting chemicals (EDCs) have been known for their ability to interfere with aspects of hormone action resulting in adverse health consequences among animals and humans; however, the effects of EDCs on human fecundity have shown inconsistent findings. This review summarizes the most recent epidemiologic literature from humans on the potential effects of female exposure to nonpersistent EDCs, specifically bisphenol A (BPA), phthalates, parabens, and triclosan, on fecundity, measured by markers of reproductive hormones, markers of ovulation or ovarian reserve, IVF outcomes, and time-to-pregnancy.

RECENT FINDINGS

Although the epidemiologic literature on this topic is growing, the evidence supporting an association between female urinary concentrations of BPA, phthalates, parabens and triclosan, and fecundity remains unclear. The heterogeneous results could be due to methodological differences in recruitment populations (fertile vs. subfertile), study designs (prospective vs. retrospective), assessment of exposure (including differences in the number and timing of urine samples and differences in the analytical methods used to assess the urinary concentrations), residual confounding due to diet or other lifestyle factors, and coexposures to other chemicals.

SUMMARY

At present, there is limited evidence to conclude that female exposure to nonpersistent EDCs affect fecundity in humans. Further studies focusing on exposure to mixtures of EDCs are needed.

The Environment and Reproductive Health (EARTH) Study: A Prospective Preconception Cohort

STUDY QUESTION

Do environmental exposures, diet and lifestyle factors impact reproductive and pregnancy outcomes among subfertile couples attending a fertility clinic?

SUMMARY ANSWER

Environmental chemicals exposure in men and women were associated with reduced fertility and a higher risk of adverse outcomes, whereas some dietary factors improved the probability of successful reproductive outcomes.

WHAT IS KNOWN ALREADY

Accumulating epidemiologic evidence has shown associations of environmental chemicals and nutritional factors with reproductive and pregnancy outcomes. However, few studies have been designed to assess these factors simultaneously, and even fewer have collected such data among both men and women in the preconception period. Furthermore, early and sensitive reproductive endpoints (e.g. fertilization, implantation, biochemical pregnancy loss) are largely unobservable in population-based designs.

STUDY DESIGN SIZE, DURATION

The Environment and Reproductive Health (EARTH) Study is an ongoing prospective preconception cohort designed to investigate the impact of environmental, nutritional and lifestyle factors in both women and men on fertility and pregnancy outcomes. The study has been ongoing since 2004 and has recruited 799 women and 487 men (447 couples; 40 men joined without female partners) as of June 2017.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The study recruits women aged 18–45 years and men aged 18–55 years seeking fertility evaluation and treatment at a large academic hospital fertility center. Women and men are eligible to join either independently or as a couple. Participants are followed from study entry throughout each fertility treatment cycle, once per trimester of pregnancy (for those achieving pregnancy), and up to labor and delivery, or until they discontinue treatment or withdraw from the study. The study prospectively collects a combination of biological samples (e.g. blood, urine, semen), self-reported questionnaire data (including a validated food frequency questionnaire) and medical information abstracted from fertility clinic and hospital records.

MAIN RESULTS AND THE ROLE OF CHANCE

Among women in this cohort, higher urinary concentrations of some phthalate metabolites were associated with reduced oocyte yields, lower likelihood of clinical pregnancy, increased risk of pregnancy loss and lower likelihood of live birth following infertility treatment. Certain urinary phthalate metabolite concentrations among men was also associated with decreased odds of implantation and live birth. Maternal soy and folate intake significantly modified the association between bisphenol A (BPA) and IVF outcomes in women. While the EARTH Study has tested many a priori hypotheses, multiple comparisons were undertaken, and we cannot rule out the possibility that some of findings may be spurious or due to chance.

LIMITATIONS REASONS FOR CAUTION

While the fertility clinic setting provides the opportunity to measure environmental exposures, diet and lifestyle factors across different windows of vulnerability and to evaluate their potential effect on critical early fertility, pregnancy and delivery outcomes, the findings may be less generalizable to naturally conceived pregnancies.

WIDER IMPLICATIONS OF THE FINDINGS

The EARTH Study is one of the few cohorts designed to examine multiple windows of vulnerability, including the paternal and maternal preconception windows and the periconception and prenatal windows, in pregnancy. It is also one of the few human studies that has assessed potential interactions between environmental exposures and dietary factors.

STUDY FUNDING/COMPETING INTEREST(S)

The EARTH Study has been funded by the National Institute of Environmental Health Sciences since its inception in 2004. The authors declare no competing interests.

TRIAL REGISTRATION NUMBER

n/a.

Effect of bisphenol A on reproductive processes: A review of in vitro, in vivo and epidemiological studies

As bisphenol A (BPA) is characterized by a pronounced influence on human hormonal regulation, particular attention has been aimed at understanding its role in reproductive processes in males and females, as well as on fetal development. Owing to the increasing number of alarming reports on the negative consequences of the presence of BPA in human surroundings, more and more studies are being undertaken to clarify the negative effects of BPA on human reproductive processes. The aim of this work was to collect and summarize data on the influence of BPA exposure on reproductive health. Based on an analysis of selected publications it was stated that there is strong proof confirming that BPA is an ovarian, uterine and prostate toxicant at a level below the lowest observed adverse effect level (50 mg kg^-1 bodyweight) as well as a level below the proposed safe level (4 μg kg^-1 bodyweight). It seems there is also reliable evidence in relation to the negative effect of BPA on sperm quality and motility. Limited evidence also pertains to the case of the potential of BPA to affect polycystic ovary syndrome occurrence. Although in epidemiological studies this disease was common, in studies on animal models such results were still not confirmed. No unambiguous results of epidemiological studies and with animal models were obtained in relation to the evaluation of associations between BPA and implantation failure in women, evaluation of associations between BPA and sexual dysfunction in men, and impact of BPA on birth rate, birth weight and length of gestation. Copyright © 2017 John Wiley & Sons, Ltd.

Effects of prenatal exposure to endocrine disruptors and toxic metals on the fetal epigenome

Exposure to environmental contaminants during pregnancy has been linked to adverse outcomes at birth and later in life. The link between prenatal exposures and latent health outcomes suggests that these exposures may result in long-term epigenetic reprogramming. Toxic metals and endocrine disruptors are two major classes of contaminants that are ubiquitously present in the environment and represent threats to human health. In this review, we present evidence that prenatal exposures to these contaminants result in fetal epigenomic changes, including altered global DNA methylation, gene-specific CpG methylation and microRNA expression. Importantly, these changes may have functional cellular consequences, impacting health outcomes later in life. Therefore, these epigenetic changes represent a critical mechanism that warrants further study.

Effects of prenatal exposure to endocrine disruptors and toxic metals on the fetal epigenome

Exposure to environmental contaminants during pregnancy has been linked to adverse outcomes at birth and later in life. The link between prenatal exposures and latent health outcomes suggests that these exposures may result in long-term epigenetic reprogramming. Toxic metals and endocrine disruptors are two major classes of contaminants that are ubiquitously present in the environment and represent threats to human health. In this review, we present evidence that prenatal exposures to these contaminants result in fetal epigenomic changes, including altered global DNA methylation, gene-specific CpG methylation and microRNA expression. Importantly, these changes may have functional cellular consequences, impacting health outcomes later in life. Therefore, these epigenetic changes represent a critical mechanism that warrants further study.