Associations between IVF outcomes and essential trace elements measured in follicular fluid and urine: a pilot study

In vivo gamete toxicology in the context of in vitro fertilization: a narrative review

IVF as a clinical method to surmount infertility has existed since the 1970s, and yet fertilization, embryo development, pregnancy, and live birth rates remain unacceptably low. Although a multitude of factors may contribute to stagnated success despite substantial advances in basic and applied IVF sciences, gamete quality is inarguably integral to IVF success rates. In this review, the authors will explore the role of environmental toxicology in impairing in vivo fertility and gamete quality prior to starting IVF that will influence downstream IVF success. In vivo contaminants of interest that may affect gamete potential in the context of IVF include heavy metals, per- and polyfluoroalkyl substances (PFAS), persistent organic pollutants (POPs), and airborne contaminants. By evaluating the current literature on reproductive toxicology and how toxic exposures may influence IVF, this review aims to provide a comprehensive reference of potential toxicological exposures for clinicians, to use in vitro and animal data to supplement correlative human studies with potential causative mechanisms, and to strengthen the case for patient assessment of toxicological risk.

Associations of Essential and Non-Essential Trace Elements' Levels in the Blood, Serum, and Urine in Women with Premature Ovarian Insufficiency

Premature ovarian insufficiency (POI) is poorly understood, with causes identified in only 25% of cases. Emerging evidence suggests links between trace elements (TEs) and POI. This study is the first to compare concentrations of manganese (Mn), copper (Cu), zinc (Zn), selenium (Se), molybdenum (Mo), arsenic (As), cadmium (Cd), mercury (Hg), and lead (Pb) across urine, serum, and whole blood in women with POI compared to healthy controls (HC), aiming to explore their distribution and potential associations with POI. This cross-sectional-case-control study enrolled 81 participants (40 POI patients and 41 healthy controls) at the University Medical Centre Ljubljana, Slovenia. Blood and urine samples were collected to quantify basic biochemical parameters using standard clinical chemistry methods and concentrations of Mn, Cu, Zn, Se, Mo, As, Cd, Hg, and Pb using inductively coupled plasma-mass spectrometry (ICP-MS). Participants also completed questionnaires on socio-demographics, medical history, lifestyle, and nutrition. Data was analyzed using the Mann-Whitney U test, Student's t-tests, Fisher exact test, logistic regression models adjusted on body mass index (BMI), age, hematocrit, and Kendall's tau correlation. Women with POI had significantly higher BMI and red blood cell (RBC) indices, including hemoglobin, hematocrit, and red cell distribution width (RDW), compared to controls. A larger proportion of POI patients resided in rural agricultural areas. Liver and kidney function assessments showed no significant differences between the groups. Adjusted models revealed that POI patients had significantly lower urinary levels of Cu, Zn, Se, Mo, Cd, Hg, and Pb than controls, while whole blood Mn levels were higher. Serum Cu levels were significantly elevated in POI patients, whereas Pb, Cd, and Hg were lower. No significant differences were observed for As. Correlation analysis showed several strong to moderate associations among TEs across biofluids, but only weak correlations were found between TEs and demographic or biochemical factors. This study suggests potential associations between TEs and POI in women. Notably, most TEs (Zn, Se, Cu, Mo, Cd, Hg, Pb) were significantly lower in the urine of the POI group, while Cu, Cd, Hg, and Pb showed significant differences in both urine and serum.

Trace elements exposure affects the outcomes of in vitro fertilization embryo transfer, a cohort study in Northern China

PURPOSE

With urbanization and industrialization process accelerated, humans are exposed more and more trace elements. This study aimed to explore the potential associations of trace elements with the outcomes of in vitro fertilization embryo transfer (IVF-ET).

METHODS

Total 181 women who underwent IVF-ET were enrolled, among which 89 women underwent fresh ET after IVF. Trace elements were measured in the serum and follicular fluid (FF) samples by inductively coupled plasma-mass spectroscopy. The associations of the levels of different trace elements with IVF-ET outcomes, including normal fertilization, high-quality embryos, and clinical pregnancy (fresh ET) were analyzed.

RESULTS

Twenty-five out of twenty-eight trace elements showed higher concentrations in the serum than those in the FF. Normal fertilization was positively associated with Cu and Mn in the FF. High-quality embryos was positively associated with Cu in the serum and FF, and Zn in the serum. Clinical pregnancy was positively associated with Ge in the serum, and inversely associated with Al, Ba, and Pb in the serum. Additionally, poor outcomes of IVF-ET should be noticed in women with FF level of Cu < 955.38 ng/mL, FF level of Mn < 3.42 ng/mL, serum level of Ge < 6.11 ng/mL, serum level of Al > 28.44 ng/mL, and serum level of Pb > 0.90 ng/mL.

CONCLUSIONS

IVF-ET outcomes were positively associated with Cu, Mn, Zn, and Ge, and inversely associated with Al and Pb. Properly controlling the exposure of relevant trace elements is necessary for patients with the need of IVF-ET.

The Impact of Minerals on Female Fertility: A Systematic Review

Female fertility and reproductive system disorders are influenced by a complex interplay of biological, physiological, and environmental factors. Minerals have emerged as crucial yet often overlooked elements that impact fertility and the prevalence of reproductive system disorders.

BACKGROUND/OBJECTIVES

This review aims to provide a comprehensive overview of the multifaceted role of minerals in female fertility, focusing on key areas such as oocyte quality, ovulation, embryo development, oxidative stress, miscarriage, hormonal regulation, environmental exposure, and in-vitro fertilization (IVF) outcomes.

METHODS

A systematic review was conducted, focusing on randomized controlled trials (RCTs), prospective cohort studies, case-control studies, nested case-control, and observational studies examining mineral supplementation and nutrition in women planning pregnancy or utilizing assisted reproduction technologies (ARTs). Relevant literature was sourced from multiple electronic databases, including PubMed, Scopus, Google Scholar, Web of Science, and the Cochrane Library, using keywords related to minerals and female fertility. The quality of studies was assessed using the Newcastle-Ottawa Scale (NCO) for non-randomized studies and the Risk of Bias (RoB) tool for RCTs. This systematic review has been registered on PROSPERO (registration number is CDR 42024547656).

RESULTS

From an initial pool of 20,830 records, 39 articles met the inclusion criteria and were analyzed. The studies addressed various reproductive outcomes influenced by minerals: embryo development, oocyte quality, oxidative stress, miscarriage, hormonal regulation, IVF outcomes, environmental exposure, and minerals as biomarkers. The analysis revealed that minerals like selenium, zinc, and copper are essential for maintaining reproductive health, while exposure to toxic metals such as cadmium and lead is detrimental.

CONCLUSIONS

This review highlights the crucial role of both mineral supplementation and serum mineral status in female fertility. The findings provide key insights for clinicians to improve reproductive health through targeted mineral intake and monitoring. Further research is needed to refine guidelines for supplementation and serum levels in women with fertility issues.

Copper homeostasis and cuproptosis in gynecological disorders: Pathogenic insights and therapeutic implications

This review comprehensively explores the complex role of copper homeostasis in female reproductive system diseases. As an essential trace element, copper plays a crucial role in various biological functions. Its dysregulation is increasingly recognized as a pivotal factor in the pathogenesis of gynecological disorders. We investigate how copper impacts these diseases, focusing on aspects like oxidative stress, inflammatory responses, immune function, estrogen levels, and angiogenesis. The review highlights significant changes in copper levels in diseases such as cervical, ovarian, endometrial cancer, and endometriosis, underscoring their potential roles in disease mechanisms and therapeutic exploration. The recent discovery of 'cuproptosis,' a novel cell death mechanism induced by copper ions, offers a fresh molecular perspective in understanding these diseases. The review also examines genes associated with cuproptosis, particularly those related to drug resistance, suggesting new strategies to enhance traditional therapy effectiveness. Additionally, we critically evaluate current therapeutic approaches targeting copper homeostasis, including copper ionophores, chelators, and nanoparticles, emphasizing their emerging potential in gynecological disease treatment. This article aims to provide a comprehensive overview of copper's role in female reproductive health, setting the stage for future research to elucidate its mechanisms and develop targeted therapeutic strategies.

Associations between follicular fluid trace elements and ovarian response during in vitro fertilization

INTRODUCTION

Exposure to trace elements has been associated with ovarian response in experimental studies. We conducted a hypothesis-generating study of associations between ovarian follicular fluid (FF) trace elements and measures of ovarian response among women using in vitro fertilization (IVF).

METHODS

We collected ovarian FF specimens from 56 women. We determined concentrations (μg/L) of 11 trace elements using inductively coupled plasma-tandem mass spectrometry. We estimated associations between women's FF trace elements per interquartile range difference, and measures of ovarian response using linear (peak estradiol (E2), baseline anti-mullerian hormone (AMH), and follicle stimulating hormone (FSH)) and negative binomial (baseline antral follicle count (AFC) and oocyte count) regression, adjusting for confounding factors. We used principal component analysis (PCA) to estimate the associations of the FF trace elements mixture. We also explored FF oxidative stress enzymes as causal mediators of the associations.

RESULTS

Higher FF cobalt was associated with greater peak E2 (mean difference = 351.48 pg/mL; 95%CI: 21.76, 724.71) and AFC (rate ratio = 1.14; 95%CI: 1.01, 1.28), and higher FF copper was associated with greater peak E2 (mean difference = 335.66 pg/mL; 95%CI: 81.77, 753.08) and oocyte count (rate ratio = 1.19; 95%CI: 1.02, 1.43). Higher FF mercury was also associated with greater peak E2 (mean difference = 410.70 pg/mL; 95%CI: 61.90, 883.39). Higher FF lead was associated with lesser AFC (rate ratio = 0.85; 95%CI: 0.73, 0.98). Using PCA, the mixture of Sr, Hg, and As was associated with higher peak estradiol, AFC, and oocyte count. FF glutathione peroxidase, paraoxonase, and arylesterase activities were inconsistent mediators of the associations, but the effect estimates were imprecise.

CONCLUSION

Our results suggest that essential and non-essential trace elements in FF were associated with ovarian response during IVF.

Higher Concentrations of Essential Trace Elements in Women Undergoing IVF May Be Associated with Poor Reproductive Outcomes Following Single Euploid Embryo Transfer

Essential trace elements are micronutrients whose deficiency has been associated with altered fertility and/or adverse pregnancy outcomes, while surplus may be toxic. The concentrations of eight essential trace elements were measured using inductively coupled mass spectrometry (ICP-MS) and assessed with respect to clinical in vitro fertilization (IVF) outcomes in a population of 51 women undergoing IVF with intracytoplasmic sperm injection (ICSI), pre-implantation genetic screening for aneuploidy (PGT-A), and single frozen euploid embryo transfer (SET/FET). Specifically, copper (Cu), zinc (Zn), molybdenum, selenium, lithium, iron, chromium, and manganese were quantified in follicular fluid and whole blood collected the day of vaginal oocyte retrieval (VOR) and in urine collected the day of VOR and embryo transfer. We found that the whole blood Cu/Zn ratio was significantly associated with superior responses to ovarian stimulation. Conversely, the whole blood zinc and selenium concentrations were significantly associated with poor ovarian response outcomes. Higher levels of whole blood zinc and selenium, urinary selenium, lithium, and iron had significant negative associations with embryologic outcomes following IVF. Regarding clinical IVF outcomes, higher urinary molybdenum concentrations the day of VOR were associated with significantly lower odds of implantation and live birth, while higher urinary Cu/Mo ratios on the day of VOR were associated with significantly higher odds of implantation, clinical pregnancy, and live birth. Our results suggest that essential trace element levels may directly influence the IVF outcomes of Spanish patients, with selenium and molybdenum exerting negative effects and copper-related ratios exerting positive effects. Additional studies are warranted to confirm these relationships in other human populations.

Using Machine Learning to Construct the Blood-Follicle Distribution Models of Various Trace Elements and Explore the Transport-Related Pathways with Multiomics Data

Permeabilities of various trace elements (TEs) through the blood-follicle barrier (BFB) play an important role in oocyte development. However, it has not been comprehensively described as well as its involved biological pathways. Our study aimed to construct a blood-follicle distribution model of the concerned TEs and explore their related biological pathways. We finally included a total of 168 women from a cohort of in vitro fertilization-embryo transfer conducted in two reproductive centers in Beijing City and Shandong Province, China. The concentrations of 35 TEs in both serum and follicular fluid (FF) samples from the 168 women were measured, as well as the multiomics features of the metabolome, lipidome, and proteome in both plasma and FF samples. Multiomics features associated with the transfer efficiencies of TEs through the BFB were selected by using an elastic net model and further utilized for pathway analysis. Various machine learning (ML) models were built to predict the concentrations of TEs in FF. Overall, there are 21 TEs that exhibited three types of consistent BFB distribution characteristics between Beijing and Shandong centers. Among them, the concentrations of arsenic, manganese, nickel, tin, and bismuth in FF were higher than those in the serum with transfer efficiencies of 1.19-4.38, while a reverse trend was observed for the 15 TEs with transfer efficiencies of 0.076-0.905, e.g., mercury, germanium, selenium, antimony, and titanium. Lastly, cadmium was evenly distributed in the two compartments with transfer efficiencies of 0.998-1.056. Multiomics analysis showed that the enrichment of TEs was associated with the synthesis and action of steroid hormones and the glucose metabolism. Random forest model can provide the most accurate predictions of the concentrations of TEs in FF among the concerned ML models. In conclusion, the selective permeability through the BFB for various TEs may be significantly regulated by the steroid hormones and the glucose metabolism. Also, the concentrations of some TEs in FF can be well predicted by their serum levels with a random forest model.

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.

Levels of trace metals and their impact on oocyte: A review

Trace metals play a vital role in a variety of biological processes, but excessive amounts can be toxic and are receiving increasing attention. Trace metals in the environment are released from natural sources, such as rock weathering, volcanic eruptions, and other human activities, such as industrial emissions, mineral extraction, and vehicle exhaust. Lifestyle, dietary habits and environmental quality are the main sources of human exposure to trace metals, which play an important role in inducing human reproductive infertility. The purpose of this review is to summarize the distribution of various trace metals in oocyte and to identify the trace metals that may cause oocyte used in the design and execution of toxicological studies.

Ascertaining sensitive exposure biomarkers of various metal(loid)s to embryo implantation

Close relationships exist between metal(loid)s exposure and embryo implantation failure (EIF) from animal and epidemiological studies. However, there are still inconsistent results and lacking of sensitive metal(loid) exposure biomarkers associated with EIF risk. We aimed to ascertain sensitive metal(loid) biomarkers to EIF and provide potential biological explanations. Candidate metal(loid) biomarkers were measured in the female hair (FH), female serum (FS), and follicular fluid (FF) with various exposure time periods. An analytical framework was established by integrating epidemiological association results, comprehensive literature searching, and knowledge-based adverse outcome pathway (AOP) networks. The sensitive biomarkers of metal(loid)s along with potential biological pathways to EIF were identified in this framework. Among the concerned 272 candidates, 45 metal(loid)s biomarkers across six time periods and three biomatrix were initially identified by single-metal(loid) analyses. Two biomarkers with counterfactual results according to literature summary results were excluded, and a total of five biomarkers were further determined from 43 remained candidates in mixture models. Finally, four sensitive metal(loid) biomarkers were eventually assessed by overlapping AOP networks information, including Se and Co in FH, and Fe and Zn in FS. AOP networks also identified key GO pathways and proteins involved in regulation of oxygen species biosynthetic, cell proliferation, and inflammatory response. Partial dependence results revealed Fe in FS and Co in FH at their low levels might be potential sensitive exposure levels for EIF. Our study provided a typical framework to screen the crucial metal(loid) biomarkers and ascertain that Se and Co in FH, and Fe and Zn in FS played an important role in embryo implantation.

Exploring the Impact of Nickel Exposure on Female Fertility

Introduction Infertility affects an estimated 186 million individuals globally and is associated with numerous mental health issues. Trace elements are essential for reproductive health, yet the role of nickel in female fertility is not well understood. Previous research has shown conflicting evidence regarding nickel's impact on ovarian function and its potential to disrupt reproductive processes. Methods We utilized data from the National Health and Nutrition Examination Survey (NHANES) focusing on a cohort of 7,839 women, with an emphasis on 1,404 women aged 18 to 35. Logistic regression was employed to investigate the relationship between urinary nickel levels and fertility status, controlling for age, BMI, and race/ethnicity. Results The fertility analysis included 880 fertile and 106 infertile women, identifying age as a significant predictor of fertility status. Nickel exposure did not demonstrate a statistically significant association with fertility. The racial distribution within the groups showed a higher proportion of non-Hispanic White women in the fertile category and Mexican American women in the infertile group, although race was not a significant predictor in the regression model. Conclusions We found no significant relationship between nickel exposure and fertility status when adjusted for race, BMI, and age. Age was the only significant factor associated with fertility. These results highlight the complexity of the interplay between environmental exposures and reproductive health, suggesting that further research is necessary to elucidate the role of nickel and other trace elements in fertility.

Alteration of epigenetic methyl and acetyl marks by postnatal chromium(VI) exposure causes apoptotic changes in the ovary of the F1 offspring

Hexavalent chromium, Cr(VI), is a heavy metal endocrine disruptor used widely in various industries worldwide and is considered a reproductive toxicant. Our previous studies demonstrated that lactational exposure to Cr(VI) caused follicular atresia, disrupted steroid hormone biosynthesis and signaling, and delayed puberty. However, the underlying mechanism was unknown. The current study investigated the effects of Cr(VI) exposure (25 ppm) during postnatal days 1-21 via dam's milk on epigenetic alterations in the ovary of F1 offspring. Data indicated that Cr(VI) disrupted follicle development and caused apoptosis by increasing DNMT3a /3b and histone methyl marks (H3K27me3 and H3K9me3) along with decreasing histone acetylation marks (H3K9ac and H3K27ac). Our study demonstrates that exposure to Cr(VI) causes changes in the epigenetic marks, partially contributing to the transcriptional repression of genes regulating ovarian development, cell proliferation (PCNA), cell survival (BCL-XL and BCL-2), and activation of genes regulating apoptosis (AIF and cleaved caspase-3), resulting in follicular atresia. The current study suggests a role for epigenetics in Cr(VI)-induced ovotoxicity and infertility.

Assessment and Exposure Analysis of Trace Metals in Different Age Groups of the Male Population in Southern Punjab, Pakistan

In developing countries, like Pakistan, the pursuit of urbanization and economic development disrupts the delicate ecosystem, resulting in additional biogeochemical emissions of heavy metals into the human habitat and posing significant health risks. The levels of these trace elements in humans remain unknown in areas at higher risk of pollution in Pakistan. In this investigation, selected trace metals including Copper (Cu), Chromium (Cr), Lead (Pb) Cadmium (Cd), Cobalt (Co), Nickel (Ni), and Arsenic (As) were examined in human hair, urine, and nail samples of different age groups from three major cities (Muzaffargarh, Multan, and Vehari) in Punjab province, Pakistan. The results revealed that the mean concentrations (ppm) of Cr (1.1) and Cu (9.1) in hair was highest in Muzaffargarh. In urine samples, the mean concentrations (μg/L) of Co (93), As (79), Cu (69), Cr (56), Ni (49), Cd (45), and Pb (35) were highest in the Multan region, while As (34) and Cr (26) were highest in Vehari. The mean concentrations (ppm) of Ni (9.2), Cr (5.6), and Pb (2.8), in nail samples were highest in Vehari; however, Multan had the highest Cu (28) concentration (ppm). In urine samples, the concentrations of all the studied metals were within permissible limits except for As (34 µg/L) and Cr (26 µg/L) in Vehari. However, in nail samples, the concentrations of Ni in Multan (8.1 ppm), Muzaffargarh (9 ppm), Vehari (9.2 ppm), and Cd (3.69 ppm) in Muzaffargarh exceeded permissible limits. Overall, the concentrations of metals in urine, nail, and hair samples were higher in adults (39-45 age group). Cr, Cu, and Ni revealed significantly higher concentrations of metals in hair and water in Multan, whereas As in water was significantly (p < 0.001) correlated with urinary As in Multan, indicating that the exposure source was region-specific.

The Influence of Follicular Fluid Metals on Assisted Reproduction Outcome

Infertility has become more common, with an increased exposure to toxic compounds including heavy metals (HM). Follicular fluid (FF) surrounds the developing oocyte in the ovary and can be analysed to assess metal content. The levels of twenty-two metals were measured in the FF of ninety-three females in a reproduction unit, and their influence on assisted reproduction technique (ART), were examined. The metals were determined by optical emission spectrophotometry. Low values of copper, zinc, aluminium, and calcium favour polycystic ovary syndrome. The relationships between the number of oocytes and metals: iron (rs=0.303; p=0.003) and calcium (rs=-0.276; p=0.007) are significant, as well as between the number of mature oocytes with iron (rs=0.319; p=0.002), calcium (rs=-0.307; p=0.003) and sodium (rs=-0.215; p=0.039) and are near to significance in the case of aluminium (rs=-0.198; p=0.057). In the group with a fertilisation rate ≤ 75%, 36% of the women presented calcium >176.62 mg/kg compared to the group with a fertilisation rate ≥ 75% where this percentage was only 10% (p=0.011). An excess of iron and calcium reduces the good quality embryo rate, and an excess of potassium impairs the blastocyst rate. If potassium is above 237.18 mg/kg and calcium is below 147.32 mg/kg, these conditions favour embryo implantation. Pregnancy is influenced by high potassium and low copper levels. Controlling exposure to toxic elements is recommended for all couples with reduced fertility or receiving an ART.

The Impact of Essential Trace Elements on Ovarian Response and Reproductive Outcomes following Single Euploid Embryo Transfer

Essential trace elements are required in extremely small amounts and obtained through diet. This research focuses on detecting major trace elements in different biofluids of sixty women undergoing ICSI with PGT-A and SET/FET at IVI-RMA, New Jersey, and assessing their impact on their IVF outcomes. Urine, plasma, and follicular fluid samples were collected on the vaginal oocyte retrieval day to measure the concentrations of eight essential trace elements (copper, zinc, molybdenum, lithium, selenium, manganese, chromium, and iron) using ICP-MS. After analysis, ovarian response and preimplantation outcomes had significant positive associations with both copper alone and the copper/zinc ratio in the follicular fluid and plasma, in addition to plasma manganese. Alternatively, elevated follicular fluid lithium concentrations were significantly associated with poor preimplantation outcomes while the urinary molybdenum concentration was significantly associated with a lower probability of implantation, clinical pregnancy, and live birth. Urinary lithium and chromium concentrations were significantly associated with a lower probability of achieving a live birth. Our results suggest that the essential trace elements present in follicular fluid, plasma, and urine of women are directly associated with their reproductive outcomes, with copper and manganese exerting positive effects and lithium and molybdenum exerting negative effects.

Blood metal/metalloid concentration of male subjects undergoing IVF/ICSI treatment outcomes: A prospective cohort study

BACKGROUND

Previous epidemiology studies reported that heavy metal/metalloid exposure is associated with the impairment of semen quality. However, it is still not clear whether the in vitro fertilization (IVF)/intracytoplasmic sperm injection (ICSI) treatment outcome will be affected after the heavy metal/metalloid exposure of the male partners.

METHODS

A prospective cohort study with a 2-year followed-up was conducted in a tertiary IVF center. A total of 111 couples undergoing IVF/ICSI treatment were initially recruited from November 2015 to November 2016. Male blood concentrations of heavy metal/metalloid including Ca, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Mo, Cd, Hg, and Pb were measured by inductively coupled plasma mass spectrometry, and the lab and pregnancy outcome data were followed up. The associations between male blood heavy metal/metalloid concentration and the clinical outcomes were analyzed by Poisson regression analysis.

RESULTS

Our results showed that none of the heavy metal/metalloid of male partners we investigated are significantly associated with the oocyte fertilization and good embryo (P ≥ 0.05); however, antral follicle count (AFC) was a protective factor for the oocyte fertilization (RR: 1.07, 95 % CI: 1.04-1.10). The blood Fe concentration of the male partner was positively associated (P < 0.05) with pregnancy in the first fresh cycle (RR:170.93, 95 % CI: 4.13-7082.04), cumulative pregnancy (RR: 23.61, 95 % CI: 3.25-171.64) and cumulative live birth (RR: 36.42, 95 % CI: 1.21-1092.54). In the first frozen embryo cycles, pregnancy was significantly associated (P < 0.05) with the blood Mn (RR: 0.01, 95 % CI:0.00-0.11) and Se concentration (RR: 0.01, 95 % CI:8.25 E-5-0.47) and female age (RR: 0.86, 95 % CI:0.75-0.99); live birth was significantly associated (P < 0.05) with the blood Mn concentration (RR: 0.00, 95 % CI: 1.14E-7-0.51).

CONCLUSIONS

Our results suggested that the higher male blood Fe concentration was positively associated with pregnancy in the fresh embryo transfer cycle, cumulative pregnancy, and cumulative live birth, whereas the higher male blood Mn and Se concentration were associated with lower chance of pregnancy and live birth in the frozen embryo transfer cycle. However, the underline mechanism of this finding still needs further investigation.

Heavy metals and metalloids exposure and in vitro fertilization: Critical concerns in human reproductive medicine

Exposures to heavy metals and metalloids have been associated with decreased fecundity and fertility in couples conceiving via assisted reproduction. Heavy metals and metalloids can alter the homeostasis of critical hormones controlling sexual maturation by binding to critical hormones and receptors. This may disrupt the time course of sexual maturation directly or indirectly affecting reproductive competence in males and females. The present review aims to provide a summarized overview of associations between heavy metal exposure, reproductive concerns, and IVF outcomes. A systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) in Google Scholar, Scopus, EMBASE and PubMed databases. Initial search produced 1,351 articles from which 30 articles were eligible to be included in the systematic review. From our results, 16 articles reported associations between selected heavy metals and IVF outcomes, while 14 articles summarized the role of heavy metals in reproductive concerns. For the studies on IVF outcomes, different human samples were examined for heavy metals. Heavy metals and metalloids (Pb, Hg, Cd, Cr, Mn, As) correlated negatively with oocyte fertilization/pregnancy rates in hair, follicular fluid, serum, urine and seminal plasma samples, while Cd and Hg in whole blood samples showed no associations. For the studies on reproductive concerns, high levels of heavy metals/metalloids were implicated in the following conditions: infertility (Cd, Pb, Ba, U), spontaneous abortion/miscarriage (Pb, Cd, Sb), congenital heart disease (Al, Mg, Cd), PCOS (As, Cd, Hg, Pb), endometriosis (Pb) and uterine leiomyomata (Hg). Taken together, the results of our study suggest that the impact of heavy metals and metalloids exposure on reproductive health may contribute to the failure rates of in vitro fertilization.

Characterizing the follicular fluid metabolome: quantifying the correlation across follicles and differences with the serum metabolome

OBJECTIVE

To compare the variability in metabolomes between the serum and follicular fluid, as well as across 3 dominant follicles.

DESIGN

Prospective cohort study.

SETTING

An academic fertility clinic in the northeastern United States, 2005-2015.

PATIENTS

One hundred thirty-five women undergoing in vitro fertilization treatment who provided a serum sample during ovarian stimulation and up to 3 follicular fluid samples during oocyte retrieval.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Samples were analyzed using liquid chromatography with high-resolution mass spectrometry and 2 chromatography columns (C18 hydrophobic negative and hydrophilic interaction chromatography [HILIC] positive). We calculated overall, feature-specific, and subject-specific correlation coefficients to describe how strongly the intensity of overlapping metabolic features were associated between the serum and follicular fluid and between the 1st-2nd, 1st-3rd, and 2nd-3rd follicles. Feature-specific correlations were adjusted for age, body mass index, infertility diagnosis, ovarian stimulation protocol, and year.

RESULT(S)

From the C18-negative column and the high-resolution mass spectrometry, 7,830 serum features and 10,790 follicular fluid features were detected in ≥20% of samples. After screening retention times and checking for 1:1 matching, 1,928 features overlapped between the 2 metabolomes. From the HILIC-positive column and the high-resolution mass spectrometry, after applying the same exclusion criteria, there were 9,074 serum features, 5,542 follicular fluid features, and 1,149 features that overlapped. When comparing the feature intensity of overlapping metabolites in the serum and the follicular fluid, the overall (C18, 0.45; HILIC, 0.63), median feature-specific (C18, 0.35; HILIC, 0.37), and median subject-specific (C18, 0.42; HILIC, 0.59) correlations were low to moderate. In contrast, among the overlapping features across all 3 follicles, the overall (C18, all 0.99; HILIC, all 0.99), median feature-specific (C18, 0.74-0.81; HILIC, 0.79-0.85), and median subject-specific (C18, 0.88-0.89; HILIC, 0.90-0.91) correlations between follicular fluid metabolomics features within a woman were high.

CONCLUSION(S)

We observed minimal overlap and weak-to-moderate correlation between metabolomic features in the serum and follicular fluid but a large overlap and strong correlation between metabolomic features across follicles within a woman. The follicular fluid appears to represent a novel matrix, distinct from serum, which may be a rich source of biologic predictors of female fertility and reproductive outcomes.

Specific lifestyle factors and in vitro fertilization outcomes in Romanian women: a pilot study

Background

Infertility is an important health concern worldwide. Although lifestyle habits and behaviors have been widely reported as predictors of IVF outcomes by previous studies, they have not been reported for Romanian women undergoing IVF. In this regard, our pilot study aimed to begin to address the data gap by assessing lifestyle predictors of in vitro fertilization (IVF) outcomes in Romanian women.

Study design

Our pilot study included 35 participants who completed a first IVF cycle at a single infertility center. We evaluated individual self-reported lifestyle habits and behaviors as predictors of IVF outcomes, and employed principal component analysis (PCA) to characterize multiple lifestyle habits and behaviors into personal care product (PCP) use, and healthy diet and physical activity patterns as predictors of IVF outcomes.

Results

Our PCA analysis showed that greater use of PCPs was associated with lower probabilities of pregnancy (RR: 0.92, 95% CI [0.87-0.98]) and live birth (RR: 0.94, 95% CI [0.88-1.01]) while, the healthy dietary habits and physical activity were associated with a higher likelihood of pregnancy, although without statistical significance (RR: 1.10, 95% CI [0.93-1.30]).

Conclusions

In this pilot study we identified associations between IVF outcomes among Romanian women and certain lifestyle habits and behaviors including stress, diet and physical activity, and certain PCP use. We also estimated the joint effects of multiple lifestyle factors using PCA and found that PCP use, healthy dietary habits and physical activity were associated with IVF outcomes.

Female infertility and diet, is there a role for a personalized nutritional approach in assisted reproductive technologies? A Narrative Review

Female infertility is a major public health concern and a global challenge. It is a disorder of the reproductive system, defined as the inability to achieve a clinical pregnancy. Nutrition and other environmental factors are found to impact reproductive health in women as well as the outcome of assisted reproductive technologies (ART). Dietary factors, such as polyunsaturated fatty acids (PUFA), fiber as well as the intake of Mediterranean diet appear to exert beneficial effects on female reproductive outcomes. The exact mechanisms associating diet to female fertility are yet to be identified, although genomic, epigenomic, and microbial pathways may be implicated. This review aims to summarize the current knowledge on the impact of dietary components on female reproduction and ART outcomes, and to discuss the relevant interplay of diet with genome, epigenome and microbial composition.

Electrophysiology of Human Gametes: A Systematic Review

PURPOSE

Oocytes and spermatozoa are electrogenic cells with the ability to respond to electrical stimuli and modulate their electrical properties accordingly. Determination of the ionic events during the gamete maturation helps to design suitable culture media for gametes in assisted reproductive technology (ART). The present systematic review focuses on the electrophysiology of human gametes during different stages of maturation and also during fertilization.

MATERIALS AND METHODS

The reports published in the English language between January 2000 and July 2021 were extracted from various electronic scientific databases following the PRISMA checklist using specific MeSH keywords.

RESULTS

Subsequent to the screening process with defined inclusion and exclusion criteria, 60 articles have been included in this review. Among them, 11 articles were directly related to the electrophysiology of human oocytes and 49 physiology department to the electrophysiology of human spermatozoa.

CONCLUSIONS

Gametes generate electrical currents by ionic exchange, particularly Na+, K+, Cl-, H+, Zn2+, Cu2+, Se2+, Mg2+, HCO3-, and Ca2+ through specific ion channels in different stages of gamete maturation. The ionic concentrations, pH, and other physicochemical variables are modulated during the gametogenesis, maturation, activation, and the fertilization process following gamete function and metabolism. The electrical properties of human gametes change during different stages of maturation. Although it is demonstrated that the electrical properties are significant regulators of cell signaling and are fundamental to gamete maturation and fertilization, their exact roles in these processes are still poorly understood. Further research is required to unveil the intricate electrophysiological processes of human gamete maturation.

Inhibition of Sirtuin-1 hyperacetylates p53 and abrogates Sirtuin-1-p53 interaction in Cr(VI)-induced apoptosis in the ovary

Environmental contamination with hexavalent chromium, Cr(VI), has been increasing in the United States as well as in developing countries. Exposure to Cr(VI) predisposes the human population to various diseases, including cancer, infertility, and developmental problems in children. Previous findings from our laboratory reported that prenatal exposure to Cr(VI) caused premature ovarian failure through p53-mediated mechanisms. Sirtuin 1 (SIRT1) is an NAD+ -dependent histone deacetylase class III. SIRT1 deacetylates several histones and non-histone proteins such as p53 and NFkB. The current study determines a role for the SIRT1-p53 network in apoptosis induced by Cr(VI) in the ovary and establishes physical interaction between SIRT1 and p53. Adult pregnant dams were given regular drinking water or Cr(VI) (10 ppm potassium dichromate in drinking water, ad libitum), and treated with SIRT1 inhibitor, EX-527 (50 mg/kg body weight, i.p.,), during 9.5 - 14.5 days post-coitum. On postnatal day-1, ovaries from F1 offspring were collected for various analyses. Results indicated that Cr(VI) increased germ cell and somatic cell apoptosis, upregulated acetyl-p53, activated the apoptotic pathway, and inhibited cell survival pathways. Cr(VI) decreased acetyl-p53-SIRT1 co-localization in the ovary. In an immortalized rat granulosa cell line SIGC, Cr(VI) inhibited the physical interaction between SIRT1 and acetyl-p53 by altering the p53:SIRT1 ratio. EX-527 exacerbated Cr(VI)-induced mechanisms. The current study shows a novel mechanism for Cr(VI)-induced apoptosis in the ovary, mediated through the p53-SIRT1 network, suggesting that targeting the p53 pathway may be an ideal approach to rescue ovaries from Cr(VI)-induced apoptosis.

The association between essential trace element (copper, zinc, selenium, and cobalt) status and the risk of early embryonic arrest among women undergoing assisted reproductive techniques

BACKGROUND

Early embryonic arrest (EEA) leads to repeated cessation of fresh cycles among infertile women undergoing in vitro fertilization (IVF). Whether the levels of some essential trace elements [copper (Cu), zinc (Zn), selenium (Se) and cobalt (Co)] in the bodies of women are related to the risk of EEA warrants study.

OBJECTIVE

Our study aimed to investigate the associations of peripheral blood levels of Cu, Zn, Se, and Co and their mixtures with the risk of EEA.

METHODS

A total of 74 EEA cases (123 IVF cycles) and 157 controls (180 IVF cycles) from the reproductive center of the First Affiliated Hospital of Anhui Medical University in Hefei, China, between June 2017 and March 2020 were included in our study. Demographic and clinical data were collected from electronic medical records. Cu, Zn, Se, and Co levels were measured in blood samples collected on the day of oocyte retrieval when infertile women entered clinical treatment for the first time using an inductively coupled plasma mass spectrometer (ICP-MS). Generalized estimating equation (GEE) models were used to evaluate the associations of four essential trace element concentrations individually with the risk of EEA, and Bayesian kernel machine regression (BKMR) was used to explore the associations between four essential trace element mixtures and the risk of EEA.

RESULTS

Se concentrations of infertile women were significantly lower in the case group compared with the control group. Co levels were significantly higher in the case group compared with the control group. The differences in Cu and Zn concentrations between the two groups were not significant. Based on single-metal models, Co was positively associated with the risk of EEA before and after adjustment for all confounders (odd ratio (OR) = 1.72, 95% confidence interval (CI): 1.18-2.52; OR = 2.27, 95% CI: 1.37-3.77, respectively), and Se was negatively associated with the risk of EEA before adjustment for all confounders (OR = 0.18, 95% CI: 0.07-0.51). BKMR analyses showed that Se was significantly and negatively associated with the risk of EEA when all the other three metals (Cu, Zn, and Co) were fixed at the 25th, 50th, or 75th percentiles, whereas Zn displayed a significant and positive association with the risk of EEA when all the other three metals (Cu, Se and Co) were fixed at the 25th, 50th, or 75th percentiles. Co did not show any effect on the risk of EEA when all the other metals (Cu, Zn, and Se) were fixed at the 25th, 50th, or 75th percentiles. In addition, an increasing trend of the joint effect of four essential trace elements on the risk of EEA was found, although it was not statistically significant.

CONCLUSION

The levels of essential trace elements (Cu, Zn, Se, and Co) might correlate with the risk of EEA to some extent. The present study might provide a real-world perspective on the relationship between essential trace elements and the risk of EEA when considering them as a single element or as mixtures.

Metal elements associate with in vitro fertilization (IVF) outcomes in 195 couples

PURPOSE

Environmental factors may affecting reproductive function reduction and embryonic development. Couples who are exposed to heavy metals for a long time may affect the outcome of in vitro fertilization (IVF). To evaluate the effect of elements on IVF outcomes, a total of 195 couples undergoing IVF were included in this study.

METHODS

Elements including V, Cr, Mn, Ni, Cu, Zn, As, Mo, Cd, Ba, Hg, Tl, Pb were measured in serum and follicular fluid (FF) samples of female and semen samples of male by Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Multiple linear regression were applied to evaluate the association between metal elements and semen quality parameters and the number of oocytes in MII stage. Poisson regression and the robust variance estimation of the generalized estimation equation were used to evaluate the association between elements and IVF outcomes.

RESULTS

The statistical results showed that Cr had a significant negative correlation with total sperm concentration (TSC) and total motile sperm count (TMC), the correlation coefficients were -0.52 (-0.27∼1.43) and -0.4(-1.24, 0.45), respectively. At the same time, Ba was significantly correlated with TSC and TMC, the correlation coefficients were 0.1(-0.15∼0.34) and 0.12(-0.13, 0.36), respectively. Cr, Ba and Pb in follicular fluid (FF) had a significant positive correlation with the number of oocytes in MII stage. The correlation coefficients were 3.15 (0.79, 5.52), 1.54 (-0.27, 3.36), 12.27 (7.49, 17.04). The Tl level of FF was significantly associated with the high probability of blastocyst formation and high-quality blastocysts (RR: 2.83, 95 % CI: 0.92∼7.95; RR: 3.12, 95 % CI: 0.64, 12.84). The Hg level (RR: 3.98, 95 % CI: 0.78∼14.77) and the Ba level in serum (RR: 12.75 95 % CI: 1.31∼89.71) were significantly correlated with high-quality blastocysts. The levels of Ni, Cu, Mo in seminal plasma of men were significantly correlated with blastocyst formation and high-quality blastocysts (RR values were all greater than 1.5). In addition, the level of Ba was significantly correlated with the high probability of blastocyst formation (RR: 1.7, 95 % CI: 1.14∼2.52).

CONCLUSION

Our results reveal that Cr, Ba and Pb may affect TSC, TMC and MII oocytes. Moreover, Ba, Cr, As, Hg and Tl in serum and Mo in seminal plasma were related to fertilization results, good embryos, blastocyst formation, high-quality embryos, and pregnancy and live birth rates. Tl in FF may related to the quality of embryonic development, Ba was an important risk factor which closely related to the outcomes of IVF in both male and female. Through our detection and statistical analysis of clinical samples, it is shown that although not all elements will affect the outcome of IVF the key elements we have selected need to arouse our attention, which benifit to the diagnosis and prevention of clinical infertility.

Urinary trace elements in association with premature ovarian insufficiency and reproductive hormones in a Chinese population

Homeostasis disturbance of trace elements has been linked to adverse reproductive consequences, including premature ovarian insufficiency (POI) in women, but limited evidence has been reported so far. This case-control study evaluated the associations between 5 common urinary trace elements [copper (Cu), manganese (Mn), Iron (Fe), Selenium (Se), and zinc (Zn)] and the odds for POI. Urinary concentrations of these 5 metals and serum levels of POI-related reproductive hormones of 169 cases and 209 healthy controls were measured. The urinary levels of Cu and Se in women with POI were significantly higher than those in the controls. The positive associations were observed between Cu levels and the odds of POI [for the medium tertile: odds ratio (OR) = 3.79, 95% CI: 1.98-7.27, p < 0.001; for the highest tertile: OR = 3.85, 95% CI: 2.00-7.41, p < 0.001]. The highest tertile of urinary Se levels was associated with increasing POI risk (for the highest tertile: OR = 2.54, 95% CI: 1.38-4.70, compared with the lowest tertile, p for trend = 0.001). In POI patients, urinary concentrations of Zn and Fe were negatively associated with serum levels of follicle-stimulating hormone (FSH). Our findings suggested that higher exposure levels of Cu and Se might lead to an increased risk of POI.

Serum zinc concentration and risk of adverse outcomes to in vitro fertilization and embryo transfer: A prospective cohort study in northern China

Zinc (Zn) plays an important role in female reproductive health. Few studies have currently assessed the effects of female Zn level on the outcome of in vitro fertilization-embryo transfer (IVF-ET). This study investigated the association between serum Zn concentration and IVF-ET outcomes, and the potential effects of some lifestyles on this association. A prospective cohort study design was adopted, and 305 women undergoing IVF-ET were recruited from two cities, Beijing and Shandong, in northern China. Fasting blood specimens were obtained on the day prior to the first treatment cycle. A questionnaire was used to collect demographic characteristics and lifestyle information. Serum Zn concentration was measured using inductively coupled plasma-mass spectrometry. Female serum Zn levels in Beijing center were found to be significantly higher than those in Shandong center. Women who failed to achieve clinical pregnancy had significantly lower Zn concentrations among Shandong subjects, but not in Beijing or the total participants in both centers. For Beijing participants, no statistically significant associations were found between Zn concentrations and the failure risk of IVF-ET [adjusted relative risk (aRR) = 0.65, 95% confidence interval (CI): 0.37-1.15]. For Shandong participants, lower Zn concentrations (< 610.3 ng/mL) were associated with a 66% increased risk of IVF-ET failure (aRR = 1.66, 95% CI: 1.10-2.51). Also, significantly positive correlations were observed between Zn concentrations and the habitual consumption of two food types, including fresh vegetables and beans or bean products, but this was not the case in Beijing. It was concluded that the effect of serum Zn concentrations on IVF-ET outcome may vary by the geographic location. Lower Zn levels might be a risk factor for IVF-ET failure among Shandong women, which can be addressed by adjusting the food intakes. These findings have implications for human infertility treatment and public health problem addressing.

Exploring reproductive associations of serum polybrominated diphenyl ether and hydroxylated brominated diphenyl ether concentrations among women undergoing in vitro fertilization

STUDY QUESTION

Are serum concentrations of polybrominated diphenyl ethers (PBDEs) and hydroxylated brominated diphenyl ethers (OH-BDEs) associated with IVF endpoints?

SUMMARY ANSWER

Positive associations were observed for BDE153 and several OH-BDEs with IVF endpoints.

WHAT IS KNOWN ALREADY

PBDEs have been voluntarily phased out of production in the USA and EU due to their persistence and toxicity to humans and ecosystems. PBDEs have been associated with implantation failure among women undergoing IVF, yet some animal studies suggest greater toxicity from their metabolites, OH-BDEs.

STUDY DESIGN, SIZE, DURATION

We evaluated a subset of 215 women (contributing 330 IVF cycles) enrolled between 2005 and 2016 in a longitudinal cohort based at Massachusetts General Hospital Fertility Center.

PARTICIPANTS/MATERIALS, SETTING, METHODS

The following PBDEs were quantified: 47, 99, 100, 153 and 154 and the following OH-BDEs: 3-OH-BDE47, 5-OH-BDE47, 6-OH-BDE47 and 4-OH-BDE49. Clinical endpoints of IVF treatments were abstracted from electronic medical records. Associations of log-transformed PBDEs and OH-BDEs with IVF outcomes were assessed using multivariable generalized mixed models and cluster weighted generalized estimating equation models adjusted for lipids, age, BMI, race, year of sample collection, IVF protocol and FSH levels. Outcomes were adjusted to represent a percent change in outcome with an increase equal to the magnitude of the difference between the 75th and 25th percentiles for each specific compound (interquartile range (IQR) increase).

MAIN RESULTS AND THE ROLE OF CHANCE

Detection frequencies were highest for congeners 47 and 153 (82% ≥ method detection limit (MDL)) and metabolites 3 and 5-OH-BDE47 and 4-OH-BDE49 (92% > MDL). PBDE and OH-BDE geometric mean concentrations declined by up to 80% between participants recruited in 2005 and those recruited in 2016. An IQR increase of BDE153 was associated with an increase in the probability of implantation (relative risk (RR) = 1.26, 95% CI: 1.16, 1.36), clinical pregnancy (RR = 1.32, 95% CI: 1.19, 1.46) and live birth (RR = 1.34; 95% CI: 1.15, 1.54). An IQR increase in 3 and 5-OH-BDE47 was associated with increased probabilities of implantation (RR = 1.52; 95% CI: 1.11, 2.09), clinical pregnancy (RR = 1.66; 95% CI: 1.17, 2.36), and live birth (RR = 1.61; 95% CI: 1.07, 2.40). When models were stratified by race (White (86%)/Other race (14%)), associations remained positive for White women, yet inverse associations were observed for Other race women. An IQR increase in BDE47 was associated with a 46% decreased probability of clinical pregnancy (95% CI: 0.31, 0.95) for Other race women.

LIMITATIONS, REASONS FOR CAUTION

Despite the long half-lives of PBDEs and OH-BDEs, exposure misclassification is possible for women who underwent multiple treatment cycles over several months or years. It is also possible another medium, such as follicular fluid would be optimal to characterize exposure. We also tested associations for multiple congeners and metabolites with multiple outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Detections of serum concentrations of PBDEs and OH-BDEs were highest in the early years of the study and suggests that the phase-out of these compounds has contributed to a decrease in exposure. The negative associations found for PBDEs and IVF outcomes among other race women suggests the potential for racial disparity. Potential racial disparities in PBDE exposure and exploration of alternative flame retardants with reproductive health outcomes should be the focus of future investigations.

STUDY FUNDING/COMPETING INTEREST(S)

Funding for this research was supported by the National Institutes of Environmental Health Sciences (NIEHS) [R01 ES009718, ES022955, ES000002 and 009718T32ES007069]. The authors have no conflicts of interest.

Variability of essential and non-essential trace elements in the follicular fluid of women undergoing in vitro fertilization (IVF)

Both essential and non-essential elements have been associated with female reproductive function in epidemiologic investigations, including among IVF populations. To date, most investigators have used blood or urine to assess biomarkers of exposure, with few employing ovarian follicular fluid (FF). FF may offer a more direct "snapshot" of the oocyte microenvironment than blood or urine, however previous studies report follicle-to-follicle variability in FF constituents that may contribute to exposure misclassification. Our objectives were to investigate sources of trace element variability, to estimate FF biomarker reliability among women undergoing IVF (n = 34), and to determine the minimum number of follicles required to estimate subject-specific mean concentrations. We measured As, Hg, Cd, Pb, Cu, Mn, Se, and Zn in FF samples using inductively coupled plasma tandem mass spectrometry. Inter-subject (between-women) variability contributed most of the variability in FF element concentrations, with ovarian, follicular, and analytical as smaller sources of variability. The proportion of variability attributable to sources between-follicles differed by age, body mass index (BMI), race, and cigarette smoking for Cu, Se, and Zn, by BMI and cigarette smoking for As, by primary infertility diagnosis for Hg, Cu, Se, and Zn, and by ovarian stimulation protocol for Mn and Se. Four to five individual follicles were sufficient to estimate subject-specific mean Cu, Se, and Zn concentrations, while >14 were necessary for As, Hg, Cd, Pb, and Mn. Overall, our results suggest that FF is a suitable source of biomarkers of As and Hg exposure in ovarian follicles. Although limited in size, our study offers the most comprehensive exploration of biological variation in FF trace elements to date and may provide guidance for future studies of ovarian trace element exposures.

Associations of toxic and essential trace elements in serum, follicular fluid, and seminal plasma with In vitro fertilization outcomes

Toxic and essential trace elements are associated with human fertility. However, limited studies have been conducted on the relationship between trace elements and in vitro fertilization (IVF) outcomes in the Chinese population. In this exploratory study, 103 couples who underwent IVF/intracytoplasmic sperm injection (ICSI) treatment in our reproductive center were recruited. Serum and follicular fluid (FF) samples and seminal plasma samples were collected from the female and male partners, respectively, on the day of oocyte retrieval. Concentrations of chromium (Cr), nickel (Ni), arsenic (As), selenium (Se), cadmium (Cd), and lead (Pb) in the specimens were measured by inductively coupled plasma-mass spectrometry. Generalized linear models were used to evaluate the associations of toxic and essential trace element levels with the intermediate parameters and outcomes of IVF at both the sex-specific and couple levels. The Cr level in the serum of the female partners was inversely associated with the count of mature oocytes retrieved (p for trend = 0.033). In terms of embryo development, As concentrations in female serum and FF were inversely associated with the probabilities to obtain good-quality cleavage embryos (p for trend < 0.01). There were significant correlations between follicular Se concentrations and seminal As concentrations and higher quality cleavage embryos (p for trend < 0.01). Moreover, a positive correlation was observed between the female serum Se concentrations and blastocyst formation (p for trend = 0.031). In contrast, a higher follicular Se level was negatively correlated with embryo development at the blastocyst stage (p for trend < 0.01). Regarding the clinical outcomes, a positive association of Se levels in seminal plasma and a negative association of follicular Cd levels was observed with the probabilities of pregnancy (p for trend = 0.006 and 0.035, respectively) and live birth (p for trend = 0.014 and 0.027, respectively). The results indicate that exposure to toxic elements (Cr, As and Cd) is associated with intermediate parameters and outcomes of IVF. Furthermore, male Se exposure may be related to better pregnancy outcomes.

Maternal Selenium, Copper and Zinc Concentrations in Early Pregnancy, and the Association with Fertility

Trace elements such as zinc, copper, and selenium are essential for reproductive health, but there is limited work examining how circulating trace elements may associate with fertility in humans. The aim of this study was to determine the association between maternal plasma concentrations of zinc, copper, and selenium, and time to pregnancy and subfertility. Australian women (n = 1060) who participated in the multi-centre prospective Screening for Pregnancy Endpoints study were included. Maternal plasma concentrations of copper, zinc and selenium were assessed at 15 ± 1 weeks' gestation. Estimates of retrospectively reported time to pregnancy were documented as number of months to conceive; subfertility was defined as taking more than 12 months to conceive. A range of maternal and paternal adjustments were included. Women who had lower zinc (time ratio, 1.20 (0.99-1.44)) or who had lower selenium concentrations (1.19 (1.01-1.40)) had a longer time to pregnancy, equivalent to a median difference in time to pregnancy of around 0.6 months. Women with low selenium concentrations were also at a 1.46 (1.06-2.03) greater relative risk for subfertility compared to women with higher selenium concentrations. There were no associations between copper and time to pregnancy or subfertility. Lower selenium and zinc trace element concentrations, which likely reflect lower dietary intakes, associate with a longer time to pregnancy. Further research supporting our work is required, which may inform recommendations to increase maternal trace element intake in women planning a pregnancy.

The Impact of Preconceptional Multiple-Micronutrient Supplementation on Female Fertility

In industrialized countries, fertility has declined in recent years to the lowest recorded levels. Identifying modifiable factors that influence human fertility, such as diet, is therefore of major clinical and public health relevance. Micronutrient status is a modifiable risk factor that may have an impact on female fertility, as essential vitamins and minerals have important roles in the physiological processes that are involved. Adequate levels are important for oocyte quality, maturation, fertilization, and implantation, whereas antioxidants are vital to reduce oxidative stress, a process known to impair fertility. In women who are diagnosed as infertile, lower than recommended levels of certain micronutrients have been reported. A similar scenario has been found in a proportion of women of childbearing age in general, some of whom may be struggling to conceive. Supplementation studies with multiple micronutrients are still scarce, but the literature suggests that supplementation before conception can help restore micronutrient status to recommended levels and reduce oxidative stress when antioxidants are included. Overall, supplementation has a small but beneficial effect on fertility in healthy and infertile women, including a shorter time to pregnancy and an increased chance of becoming pregnant. Nevertheless, many studies are small or observational, and adequately powered randomized controlled trials of supplementation with multiple micronutrients are necessary to confirm any definite effects on fertility. This review substantiates the potential benefits of micronutrient supplementation beyond the prevention of neural tube defects, the traditionally viewed value of prenatal vitamin use.

Toxic Metal and Trace Element Concentrations in Blood and Outcome of In Vitro Fertilization in Women

The aim of this study was to investigate the association of trace element and toxic metal concentrations in blood and the outcome of in vitro fertilization (IVF). The study included 104 consecutive patients that underwent assisted reproductive technology (ART) procedures. The following parameters were determined: cadmium (Cd), mercury (Hg), arsenic (As), and lead (Pb); and copper (Cu), zinc (Zn), selenium (Se), and magnesium (Mg). Serum samples were obtained before commencing stimulation. Patients with smoking habit had significantly higher Pb concentrations (P = 0.022), as well as higher concentrations of As and Hg but not significantly. All subjects were divided into groups of pregnant and nonpregnant patients. Pregnant patients had lower mean values of Mg (P = 0.009), As (P < 0.05), and Pb (P = 0.034), compared to nonpregnant, and a significant correlation between pregnancy outcome and concentrations of Mg, Cd, and Pb was found. Women who had had delivered had lower Mg (P = 0.009) and Cd (P = 0.014) concentrations. There was a significant correlation of the negative outcome of IVF procedure with higher concentrations of Pb (P = 0.046) and Cd (P = 0.012). In conclusion, our results suggest that there is a difference in Mg, Pb, and Cd concentrations between pregnant and nonpregnant women. There was no association between toxic metals and number and quality of oocytes and embryos, while there was with fertilization rate. Concerning trace elements, we did not find the correlation of trace elements with oocyte number and quality, nor with a number of fertilized oocytes, except for Cu. Patients who were pregnant had lower concentrations of Mg.

The Influences of Chromium Supplementation on Glycemic Control, Markers of Cardio-Metabolic Risk, and Oxidative Stress in Infertile Polycystic ovary Syndrome Women Candidate for In vitro Fertilization: a Randomized, Double-Blind, Placebo-Controlled Trial

This study was carried out to investigate the effects of chromium intake on glycemic control, markers of cardio-metabolic risk, and oxidative stress in infertile polycystic ovary syndrome (PCOS) women candidate for in vitro fertilization (IVF). This randomized double-blind, placebo-controlled trial was done among 40 subjects with infertile PCOS candidate for IVF, aged 18-40 years old. Individuals were randomly allocated into two groups to take either 200 μg/day of chromium (n = 20) or placebo (n = 20) for 8 weeks. Biochemical parameters were assessed at baseline and at end-of-trial. Compared with the placebo, taking chromium supplements led to significant reductions in fasting plasma glucose (- 2.3 ± 5.7 vs. + 0.9 ± 3.1 mg/dL, P = 0.03), insulin levels (- 1.4 ± 2.1 vs. + 0.4 ± 1.7 μIU/mL, P = 0.004), homeostatic model of assessment for insulin resistance (- 0.3 ± 0.5 vs. + 0.1 ± 0.4, P = 0.005), and a significant increase in quantitative insulin sensitivity check index (+ 0.004 ± 0.008 vs. - 0.001 ± 0.008, P = 0.03). In addition, chromium supplementation significantly decreased serum triglycerides (- 19.2 ± 33.8 vs. + 8.3 ± 21.7 mg/dL, P = 0.004), VLDL- (- 3.8 ± 6.8 vs. + 1.7 ± 4.3 mg/dL, P = 0.004) and total cholesterol concentrations (- 15.3 ± 26.2 vs. - 0.6 ± 15.9 mg/dL, P = 0.03) compared with the placebo. Additionally, taking chromium supplements was associated with a significant increase in plasma total antioxidant capacity (+ 153.9 ± 46.1 vs. - 7.8 ± 43.9 mmol/L, P < 0.001) and a significant reduction in malondialdehyde values (-0.3 ± 0.3 vs. + 0.1 ± 0.2 μmol/L, P = 0.001) compared with the placebo. Overall, our study supported that chromium administration for 8 weeks to infertile PCOS women candidate for IVF had beneficial impacts on glycemic control, few variables of cardio-metabolic risk, and oxidative stress.

Urinary metabolomics reveals novel interactions between metal exposure and amino acid metabolic stress during pregnancy

Pregnant women are a unique group undergoing profound structural modifications in uterus, breast, adipose tissue and extracellular fluids. Amino acid metabolic stress is a unique physical process that occurs during pregnancy. Metals constitute a fundamental part of the maternal body and have a universal effect on amino acid metabolism. However, the exact interaction between metals and amino acid metabolism during pregnancy is unknown. The aim of the present study was to determine the correlations of metals with amino acid metabolic intermediates in the urine of 232 healthy pregnant women in their first, second and third trimesters during normal pregnancy. Sixteen metals in the urine of 232 healthy pregnant women in their first, second and third trimesters were quantified using inductively coupled plasma mass spectrometry (ICP-MS). An ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometer (UPLC-QTOFMS)-based metabolomics approach was conducted to detect intermediate products involved in amino acid metabolism during the entire pregnancy period. A panel regression model was established to investigate the relationship between urine metals and amino acid metabolism. Seven metals-cadmium, cobalt, copper, cesium, manganese, thallium and vanadium-showed significant association with amino acid metabolic intermediates, including 2-oxoarginine, 3-indoleacetonitrile, indole, indole-5,6-quinone, N2-succinyl-l-glutamic acid 5-semialdehyde, N-methyltryptamine and N-succinyl-l,l-2,6-diaminopimelate, in the healthy pregnant women. These findings indicated that exposure to cadmium, cobalt, copper, cesium, manganese, thallium and vanadium significantly affected the metabolic status of tryptophan, arginine, proline, tyrosine and lysine metabolism in the maternal body during normal pregnancy.