Mixtures of persistent organic pollutants and ovarian function in women undergoing IVF

Expert opinion on refined and extended key performance indicators for individualized ovarian stimulation for assisted reproductive technology

OBJECTIVE

To assess the adequate ovarian follicular development and oocyte recovery between ovarian potential (antral follicle count [AFC]) before the start of ovarian stimulation (OS) and oocyte quantity and quality at oocyte retrieval. A holistic overview of the current key performance indicators (KPIs) was applied to identify the complementary strengths and identify where the current repertoire can be expanded.

DESIGN

Expert opinion.

INTERVENTION

None.

MAIN OUTCOME MEASURES

To formulate a proposal for a refined and expanded repertoire of KPIs for individualized OS for assisted reproductive technology.

RESULTS

The performance and outcomes of OS on ovarian follicular development can be evaluated through the application of defined KPIs. Current KPIs for OS are the ovarian sensitivity index, follicular output rate (FORT), oocyte retrieval rate, and follicle-to-oocyte index (FOI). Notably, there are no specific KPIs dedicated to the assessment of follicular development (i.e., recruitment, selection, growth, and dominance). In light of this, we recommend expanding the current KPIs for OS to include "early FORT" (accounting for the number of follicles measuring ≥10 to 11 mm on day 5/6 of OS relative to AFC) and "modified FORT" (the ratio between the number of follicles measuring ≥12 mm at the time of oocyte maturation triggering and AFC); the extension of oocyte retrieval rate to include two discrete categories at oocyte retrieval-follicles measuring ≥12 mm and ≥16 mm-to ensure that all responsive follicles are accounted for; and FOI to be measured at oocyte maturation triggering and oocyte retrieval ("advanced FOI").

CONCLUSION

Once validated and adopted in clinical practice, we envisage that the proposed expanded KPIs measuring the effect of OS on follicular development (recruitment, selection, growth, and dominance) will increase the understanding of the relationship between ovarian reserve, measured by AFC, and oocyte quantity and quality at oocyte retrieval. This understanding will enable physicians to better evaluate the direct effect of different gonadotropins and doses on ovarian response, leading to a more personalized approach to OS in the context of assisted reproductive technology treatment.

Distribution of Environmental Phenols into Follicular Fluid and Urine of Women Attending Infertility Clinic

Infertility and environmental pollution are two globally prevalent and related issues. To explore women's reproductive health, the composition of follicular fluid (FF) has been studied and it was found that changes to its composition, including the presence of exogenous chemicals, can adversely affect the fertilization process. Two groups of women (idiopathic infertility and controls) who were patients at a fertility clinic were recruited for this study. Samples of urine and FF were gathered from each participant to determine the concentration of 14 common phenols (four parabens, six bisphenols, two benzophenones, and two naphthols). Associations between phenol concentrations (free and total) in both matrices were described using Spearman's correlation coefficient and were compared between two groups by the Mann-Whitney U test. Eight phenols were quantified in more than 50% of the urine samples, while only three parabens were quantified in hydrolyzed FF samples, and only methylparaben was quantified in non-hydrolyzed FF samples. Conjugates were the predominant form in FF samples. However, a significant correlation of 0.533 (p < 0.0001) was observed between free and total methylparaben concentrations in FF. Differences in concentrations between cases and controls in both matrices were not statistically significant, except for benzophenone-3 in urine, with a higher median observed in the control group (p = 0.04). The total paraben concentrations in urine and FF samples were rather weakly correlated (r = 0.232-0.473), implying that urine concentrations may not be appropriate for predicting their concentration in FF.

Exposure to Environmental Chemicals and Infertility Among US Reproductive-Aged Women

Environmental chemical exposure has been rising over the past few decades but its impact on fertility remains uncertain. We assessed exposures to 23 common chemicals across a range of sociodemographic characteristics and their relationship with self-reported infertility. The analytic sample was non-pregnant women aged 18-49 years without a history of hysterectomy or oophorectomy (n = 2579) from the National Health and Nutrition Examination Survey (2013-2016). Environmental chemical exposure was assessed with biospecimens and dichotomized as high and low levels of exposure based on the median. Logistic regression models estimated the adjusted odds ratio (aOR) and 95% confidence intervals (CIs) for the association between high levels of exposure and infertility, adjusted for age, race, education level, family income, and smoking status. We observed associations between infertility and cadmium [aOR: 1.88; 95% CI: 1.02-3.47] and arsenic [aOR: 1.88 (1.05-3.36)]. Two pesticides hexachlorobenzene [OR: 2.04 (1.05-3.98)] and oxychlordane [OR: 2.04 (1.12-3.69)] were also associated with infertility in unadjusted analyses. There were negative associations with two Per- and polyfluoroalkyl substances with n-perfluorooctanoic acid [aOR: 0.51: (0.30-0.86)] and n-perfluorooctane sulfonic acid [aOR: 0.51: (0.26-0.97). Specific chemicals may contribute to infertility risk, highlighting the need for targeted public health strategies to mitigate exposure.

Environmental Exposure to Persistent Organic Pollutants and Its Association with Endometriosis Risk: Implications in the Epithelial-Mesenchymal Transition Process

We aimed to explore the relationship of adipose tissue concentrations of some persistent organic pollutants (POPs) with the risk of endometriosis and the endometriotic tissue expression profile of genes related to the endometriosis-related epithelial-mesenchymal transition (EMT) process. This case-control study enrolled 109 women (34 cases and 75 controls) between January 2018 and March 2020. Adipose tissue samples and endometriotic tissues were intraoperatively collected to determine concentrations of nine POPs and the gene expression profiles of 36 EMT-related genes, respectively. Associations of POPs with endometriosis risk were explored with multivariate logistic regression, while the relationship between exposure and gene expression profiles was assessed through Spearman correlation or Mann-Whitney U tests. After adjustment, increased endometriosis risk was associated with p,p'-DDT, PCB-180, and ΣPCBs. POP exposure was also associated with reduced gene expression levels of the CLDN7 epithelial marker and increased levels of the ITGB2 mesenchymal marker and a variety of EMT promoters (HMGA1, HOXA10, FOXM1, DKK1, CCR1, TNFRSF1B, RRM2, ANG, ANGPT1, and ESR1). Our findings indicate that exposure to POPs may increase the risk of endometriosis and might have a role in the endometriosis-related EMT development, contributing to the disease onset and progression. Further studies are warranted to corroborate these findings.

Advances in polychlorinated biphenyls-induced female reproductive toxicity

Polychlorinated biphenyls (PCBs) are a class of endocrine-disrupting chemicals (EDCs) widely present in the environment. PCBs have been of concern due to their anti/estrogen-like effects, which make them more toxic to the female reproductive system. However, there is still a lack of systematic reviews on the reproductive toxicity of PCBs in females, so the adverse effects and mechanisms of PCBs on the female reproductive system were summarized in this paper. Our findings showed that PCBs are positively associated with lower pregnancy rate, hormone disruption, miscarriage and various reproductive diseases in women. In animal experiments, PCBs can damage the structure and function of the ovaries, uterus and oviducts. Also, PCBs could produce epigenetic effects and be transferred to the offspring through the maternal placenta, causing development retardation, malformation and death of embryos, and damage to organs of multiple generations. Furthermore, the mechanisms of PCBs-induced female reproductive toxicity mainly include receptor-mediated hormone disorders, oxidative stress, apoptosis, autophagy, and epigenetic modifications. Finally, we also present some directions for future research on the reproductive toxicity of PCBs. This detailed information provided a valuable reference for fully understanding the reproductive toxicity of PCBs.