Does an increased body mass index affect endometrial gene expression patterns in infertile patients? A functional genomics analysis

Metabolic disparities between obese and non-obese patients with polycystic ovary syndrome: implications for endometrial receptivity indicators

OBJECTIVE

To investigate the differences in the metabolic indicators and sex hormones between obese and non-obese patients with polycystic ovary syndrome (PCOS), and their impacts on endometrial receptivity (ER).

METHODS

We selected 255 individuals with PCOS, and categorized them into the obese groups, including the OP group (obese patients with PCOS) and the ON group (obese patients without PCOS), and selected 64 individuals who were categorized in the non-obese groups, namely, the control groups, which comprise the NP group (non-obese patients with PCOS) and the NN group(non-obese patients without PCOS). The one-way analysis of variance (ANOVA) and Mann-Whitney U tests were used to compare the metabolic indicators, and sex hormone-associated and ER-associated indicators between the groups. The correlation between the aforementioned clinical markers and ER was analyzed using the Pearson's correlation coefficient.

RESULTS

(1) In comparison with the NP group, the OP group exhibited higher levels (p < .01) of free androgen index (FAI), anti-müllerian hormone (AMH), fasting insulin (FINS), insulin level within 60 min, 120 min, and 180 min-60minINS, 120minINS, and 180minINS, respectively, fasting blood glucose (FBG), blood glucose level within two hours (2hGlu), homeostatic model assessment for insulin resistance (HOMA-IR), triglyceride (TG), low-density lipoprotein cholesterol (LDL-C), waist-to-hip ratio (WHR), waist circumference, hip circumference, the ratio of the maximum blood flow velocity of the uterine artery during systole to the blood flow velocity of the uterine artery at the end of diastole (uterine artery S/D), and blood flow resistance index (RI) of the uterine artery. In comparison with the NP group, the OP group exhibited lower levels (p < .01) of sex hormone binding globulin (SHBG), dehydroepiandrosterone (DHEA), high molecular weight adiponectin (HMWA), and high-density lipoprotein cholesterol (HDL-C). (2) In the PCOS group, RI was significantly positively correlated with FAI, FINS, 120minINS, HOMA-IR, and WHR (p < .01), and significantly negatively correlated with SHBG, HDL-C, and HMWA (p < .01); uterine artery S/D was significantly positively correlated with FAI, FINS, 2hGlu, HOMA-IR, LDL-C, and WHR (p < .01), significantly positively correlated with 120minINS and FBG (p < .05), and significantly negatively correlated with SHBG and HMWA (p < .01).

CONCLUSION

(1) The OP group exhibited obvious metabolic disorders and poor ER, which was manifested as low levels of SHBG and HMWA, and high levels of FAI, HOMA-IR, WHR, uterine artery S/D, and RI. (2) In patients with PCOS, there was a substantial correlation between ER-associated indicators RI and uterine artery S/D and FAI, FINS, 120minINS, HOMA-IR, WHR, SHBG, and HMWA.

The endometrial transcriptome of infertile women with and without implantation failure

INTRODUCTION

Implantation failure after transferring morphologically "good-quality" embryos in in vitro fertilization/intracytoplasmic sperm injection (IVF/ICSI) may be explained by impaired endometrial receptivity. Analyzing the endometrial transcriptome analysis may reveal the underlying processes and could help in guiding prognosis and using targeted interventions for infertility. This exploratory study investigated whether the endometrial transcriptome profile was associated with short-term or long-term implantation outcomes (ie success or failure).

MATERIAL AND METHODS

Mid-luteal phase endometrial biopsies of 107 infertile women with one full failed IVF/ICSI cycle, obtained within an endometrial scratching trial, were subjected to RNA-sequencing and differentially expressed genes analysis with covariate adjustment (age, body mass index, luteinizing hormone [LH]-day). Endometrial transcriptomes were compared between implantation failure and success groups in the short term (after the second fresh IVF/ICSI cycle) and long term (including all fresh and frozen cycles within 12 months). The short-term analysis included 85/107 women (33 ongoing pregnancy vs 52 no pregnancy), excluding 22/107 women. The long-term analysis included 46/107 women (23 'fertile' group, ie infertile women with a live birth after ≤3 embryos transferred vs 23 recurrent implantation failure group, ie no live birth after ≥3 good quality embryos transferred), excluding 61/107 women not fitting these categories. As both analyses drew from the same pool of 107 samples, there was some sample overlap. Additionally, cell type enrichment scores and endometrial receptivity were analyzed, and an endometrial development pseudo-timeline was constructed to estimate transcriptomic deviations from the optimum receptivity day (LH + 7), denoted as ΔWOI (window of implantation).

RESULTS

There were no significantly differentially expressed genes between implantation failure and success groups in either the short-term or long-term analyses. Principal component analysis initially showed two clusters in the long-term analysis, unrelated to clinical phenotype and no longer distinct following covariate adjustment. Cell type enrichment scores did not differ significantly between groups in both analyses. However, endometrial receptivity analysis demonstrated a potentially significant displacement of the WOI in the non-pregnant group compared with the ongoing pregnant group in the short-term analysis.

CONCLUSIONS

No distinct endometrial transcriptome profile was associated with either implantation failure or success in infertile women. However, there may be differences in the extent to which the WOI is displaced.

The Impacts of Inflammatory and Autoimmune Conditions on the Endometrium and Reproductive Outcomes

Background: A healthy pregnancy begins with an adequate endometrial state, even before the arrival of a blastocyst. Proper endometrial priming and the development of a tolerogenic decidua are key steps in creating the perfect environment for implantation and pregnancy. In these processes, the involvement of the maternal immune system seems to be of great relevance, modulating the different decidual immune populations to prepare the endometrium for a potential pregnancy. However, certain local pathologies of an inflammatory and autoimmune nature appear to have a direct impact on these phenomena, thus altering patients' reproductive outcomes. Methods: This literature review analyzes original articles, reviews, systematic reviews, and meta-analyses published between 1990 and 2024, concerning the impact of different inflammatory and autoimmune conditions on endometrial status and fertility. The included papers were obtained from Medline (Pubmed) and the Cochrane library. Results: There is evidence that endometriosis, adenomyosis, and chronic endometritis, through the promotion of a chronic inflammatory environment, are capable of altering endometrial immune populations, and, thus, processes essential for early pregnancy. Among other effects, these conditions have been linked to impaired decidualization, alterations in progesterone responsiveness, and hindered placentation. Similarly, antiphospholipid syndrome (APS), thyroid dysfunction, diabetes, and other pathologies related to glucose and gluten metabolism, due to their autoimmune nature, also appear to have a local impact on the uterine environment, affecting reproductive success through different mechanisms, including altered hormonal response and, again, impaired decidualization. Conclusions: The management of inflammatory and autoimmune diseases in assisted reproduction patients is gaining importance due to their direct impact on the endometrium. It is necessary to follow current expert recommendations and established therapeutic approaches in order to improve patients' prospects, ranging from antibiotic treatment in chronic endometritis to heparin and aspirin in APS, as well as hormonal treatments for endometriosis/adenomyosis or a gluten-free diet in celiac disease. All of them and the rest of the therapeutic perspectives, both current and under investigation, are presented throughout this work, assessing the possible improvements for reproductive outcomes.

The Molecular Link between Obesity and the Endometrial Environment: A Starting Point for Female Infertility

Female infertility constitutes a growing health problem in developing countries and could be associated with several possible causes including reproductive disorders, congenital malformations, infections and hormonal dysfunction. Nonetheless, a series of additional factors can also negatively impact female fertility and are represented by chronic exposure to environmental pollutants, stress, unhealthy lifestyle choices such as cigarette smoking and, among others, obesity. Excess weight is associated with several chronic diseases, and growing evidence demonstrates that it can compromise reproductive physiology due to its influence on endometrial gene expression and receptivity. Thus, the current review of the literature mainly focused on how obesity can impair uterine receptivity, mostly from a molecular point of view throughout the window of implantation (WOI) period at an endometrial level. It was also highlighted that an obesity-related increase in adipose tissue may lead to a modulation in the expression of multiple pathways, which could cause a hostile endometrial environment with a consequent negative impact on the uterine receptivity and the establishment of pregnancy. Thanks to the use of the endometrial receptivity assay (ERA), a specific microarray that studies the expression of a series of genes, it is now possible to evaluate the endometrial status of patients with infertility problems in a more detailed manner. Moreover, female fertility and endometrial receptivity could be affected by endometriosis, a chronic benign gynecological disease, whose cause-and-effect relationship to obesity is still uncertain. Therefore, further investigations would be required to better elucidate these mechanisms that govern embryo implantation and could be potentially useful for the generation of new strategies to overcome implantation failure and improve the pregnancy rates in obese women.

Rapid generation of functional nanovesicles from human trophectodermal cells for embryo attachment and outgrowth

Extracellular vesicles (EVs) are important mediators of embryo attachment and outgrowth critical for successful implantation. While EVs have garnered immense interest in their therapeutic potential in assisted reproductive technology by improving implantation success, their large-scale generation remains a major challenge. Here, we report a rapid and scalable production of nanovesicles (NVs) directly from human trophectoderm cells (hTSCs) via serial mechanical extrusion of cells; these NVs can be generated in approximately 6 h with a 20-fold higher yield than EVs isolated from culture medium of the same number of cells. NVs display similar biophysical traits (morphologically intact, spherical, 90-130 nm) to EVs, and are laden with hallmark players of implantation that include cell-matrix adhesion and extracellular matrix organisation proteins (ITGA2/V, ITGB1, MFGE8) and antioxidative regulators (PRDX1, SOD2). Functionally, NVs are readily taken up by low-receptive endometrial HEC1A cells and reprogram their proteome towards a receptive phenotype that support hTSC spheroid attachment. Moreover, a single dose treatment with NVs significantly enhanced adhesion and spreading of mouse embryo trophoblast on fibronectin matrix. Thus, we demonstrate the functional potential of NVs in enhancing embryo implantation and highlight their rapid and scalable generation, amenable to clinical utility.

Obesity in prenatal medicine: a game changer?

Obesity is recognized by the World Health Organization (WHO) as a disease in its own right. Moreover, obesity is an increasingly concerning public health issue across the world and its prevalence is rising amongst women of reproductive age. The fertility of over-weight and obese women is reduced and they experience a higher rate of miscarriage. In pregnant women obesity not only increases the risk of antenatal complications, such as preeclampsia and gestational diabetes, but also fetal abnormalities, and consequently the overall feto-maternal mortality. Ultrasound is one of the most valuable methods to predict and evaluate pregnancy complications. However, in overweight and obese pregnant women, the ultrasound examination is met with several challenges, mainly due to an impaired acoustic window. Overall obesity in pregnancy poses special challenges and constraints to the antenatal care and increases the rate of pregnancy complications, as well as complications later in life for the mother and child.

Frozen embryo transfer outcomes decline with increasing female body mass index in female but not male factor infertility: analysis of 56,564 euploid blastocyst transfers

OBJECTIVE

To evaluate the association of body mass index (BMI) with cycle outcomes after euploid frozen blastocyst transfer.

DESIGN

Retrospective cohort study.

SETTING

Not applicable.

PATIENT(S)

A total of 56,564 first single autologous euploid frozen embryo transfers from the 2016-2019 Society for Assisted Reproductive Technology database were analyzed using BMI and using World Health Organization BMI cohorts. Subanalyses were performed on cycles among patients with a sole diagnosis of polycystic ovary syndrome (PCOS) (n = 4,626) and among patients with only a male factor (n = 10,854).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Clinical pregnancy, pregnancy loss, and live birth (LB).

RESULT(S)

Success rates and adjusted odds ratios (aORs) with 95% confidence intervals (CIs) for all outcomes were most favorable among those with normal BMI and progressively worsened with increasing BMI. These trends persisted among patients with PCOS for clinical pregnancy (aOR, 0.99; 95% CI, 0.98-0.997), pregnancy loss (aOR, 1.02; 95% CI, 1.01-1.04), and LB (aOR, 0.98; 95% CI, 0.97-0.99), but not among patients with a male factor only for clinical pregnancy (aOR, 1.00; 95% CI, 0.99-1.01), pregnancy loss (aOR, 1.01; 95% CI, 0.99-1.03), or LB (aOR, 0.99; 95% CI, 0.98-1.00).

CONCLUSION(S)

In the largest cohort to date, increasing BMI was associated with decreased pregnancy and LB and increased pregnancy loss after euploid frozen embryo transfers among the entire cohort and among patients with a sole diagnosis of PCOS; however, these results were attenuated among patients with a sole diagnosis of male factor infertility, suggesting that associated female infertility diagnoses and not BMI alone may underlie this trend.

Detrimental actions of obesity-associated advanced glycation end-products on endometrial epithelial cell proliferation are alleviated by antioxidants

RESEARCH QUESTION

Advanced glycation end-products (AGE) are elevated in the uterine environment of obese infertile women. Can the detrimental effects of AGE on endometrial epithelial cells be mitigated with therapeutics, and recapitulated in a more physiologically relevant primary model (organoids)?

DESIGN

Human endometrial epithelial cells (ECC-1) were exposed to AGE at concentrations physiologically representative of uterine fluid in lean or obese individuals, and three potential therapeutics: 25 nmol/l receptor for AGE (RAGE) antagonist FPS-ZM1, 100 μmol/l metformin, or a combination of antioxidants (10 μmol/l N-acetyl-l-cysteine, 10 μmol/l N-acetyl-l-carnitine and 5 μmol/l α-lipoic acid). Real-time cell analysis (xCELLigence, ACEA Biosciences) determined the rate of adhesion and proliferation. The proliferation of organoid-derived cells and secretion of cytokines from organoids was characterized in the presence of AGE (n = 5). The uterine fluid of women undergoing assisted reproduction was profiled for AGE-associated inflammatory markers (n = 77).

RESULTS

ECC-1 proliferation was reduced by AGE from obese versus lean conditions and vehicle control (P = 0.04 and P < 0.001, respectively), and restored to a proliferation corresponding to lean conditions by antioxidants. AGE influenced organoid derived primary endometrial epithelial cell proliferation in a donor-dependent manner. AGE increased the organoid secretion of the proinflammatory cytokine CXCL16 (P = 0.006). Clinically, CXCL16 correlated positively to maternal body mass index (R = 0.264, P = 0.021) and intrauterine glucose concentration (R = 0.736, P < 0.0001).

CONCLUSIONS

Physiologically relevant concentrations of AGE alter endometrial epithelial cell function. Antioxidants restore the rate of proliferation of AGE-treated endometrial epithelial (ECC-1) cells. Primary endometrial epithelial cells, cultured as organoids, demonstrate altered proliferation and CXCL16 secretion in the presence of AGE equimolar with the uterine fluid from obese individuals.

The effect of obesity on uterine receptivity is mediated by endometrial extracellular vesicles that control human endometrial stromal cell decidualization and trophoblast invasion

The objectives of the present study were to determine whether obesity impacts human decidualization and the endometrial control of trophoblast invasion (both of which are required for embryo implantation) and evaluate the potential involvement of endometrial extracellular vesicles (EVs) in the regulation of these physiological processes. Using primary human cell cultures, we first demonstrated that obesity is associated with significantly lower in vitro decidualization of endometrial stromal cells (ESCs). We then showed that a trophoblastic cell line's invasive ability was greater in the presence of conditioned media from cultures of ESCs from obese women. The results of functional assays indicated that supplementation of the culture medium with EVs from nonobese women can rescue (at least in part) the defect in in vitro decidualization described in ESCs from obese women. Furthermore, exposure to endometrial EVs from obese women (vs. nonobese women) was associated with significantly greater invasive activity by HTR-8/SVneo cells. Using mass-spectrometry-based quantitative proteomics, we found that EVs isolated from uterine supernatants of biopsies from obese women (vs. nonobese women) presented a molecular signature focused on cell remodelling and angiogenesis. The proteomics analysis revealed two differentially expressed proteins (fibronectin and angiotensin-converting enzyme) that might be involved specifically in the rescue of the decidualization capacity in ESCs from obese women; both of these proteins are abundantly present in endometrial EVs from nonobese women, and both are involved in the decidualization process. In conclusion, our results provided new insights into the endometrial EVs' pivotal role in the poor uterine receptivity observed in obese women.

ART outcomes in lean compared to obese phenotypes of polycystic ovarian syndrome

RESEARCH QUESTION

To investigate differences in reproductive outcomes among IVF patients with lean compared to obese polycystic ovarian syndrome (PCOS) phenotypes.

DESIGN

A retrospective cohort study of patients with PCOS who underwent IVF in a single, academically affiliated infertility center in the USA between December 2014 and July 2020. The diagnosis of PCOS was assigned based on Rotterdam criteria. Patients were designated as lean (< 25) or overweight/obese (≥ 25) PCOS phenotype based on BMI (kg/m2) at cycle start. Baseline clinical and endocrinologic laboratory panel, cycle characteristics, and reproductive outcomes were analyzed. The cumulative live birth rate included up to 6 consecutives cycles. A Cox proportional hazards model and Kaplan-Meier curve for estimating live birth rates were used to compare the two phenotypes.

RESULTS

A total of 1395 patients who underwent 2348 IVF cycles were included. The mean (SD) BMI was 22.7 (2.4) in the lean and 33.8 (6.0) in the obese group (p < 0.001). A number of endocrinological parameters were similar between lean and obese phenotypes: total testosterone 30.8 ng/dl (19.5) vs 34.1 (21.9), p > 0.02 and pre-cycle hemoglobin A1C 5.33% (0.38) vs 5.51% (0.51) p > 0.001, respectively. The CLBR was higher in those with a lean PCOS phenotype: 61.7% (373/604) vs 54.0% (764/1414) respectively. Miscarriage rates were significantly higher for O-PCOS patients (19.7% (214/1084) vs 14.5% (82/563) p < 0.001) and the rate of aneuploids was similar (43.5%, 43.8%, p = 0.8). A Kaplan-Meier curve estimating the proportion of patients with a live birth was higher in the lean group (log-rank test p = 0.013). After adjusting for potential confounders, the lean phenotype was associated with an increased hazard ratio for live birth: HR = 1.38 p < 0.001.

CONCLUSIONS

Lean PCOS phenotype is associated with a significantly higher CLBR compared to their obese counterparts. Miscarriage rates were significantly higher among obese patients, despite comparable pre-cycle HBA1C and similar aneuploidy rates in patients who underwent PGT-A.

Prediction of risk factors for first trimester pregnancy loss in frozen-thawed good-quality embryo transfer cycles using machine learning algorithms

PURPOSE

Can the risk factors that cause first trimester pregnancy loss in good-quality frozen-thawed embryo transfer (FET) cycles be predicted using machine learning algorithms?

METHODS

This is a retrospective cohort study conducted at Sisli Memorial Hospital, ART and Reproductive Genetics Center, between January 2011 and May 2021. A total of 3805 good-quality FET cycles were included in the study. First trimester pregnancy loss rates were evaluated according to female age, paternal age, body mass index (BMI), diagnosis of infertility, endometrial preparation protocols (natural/artificial), embryo quality (top/good), presence of polycystic ovarian syndrome (PCOS), history of recurrent pregnancy loss (RPL), recurrent implantation failure (RIF), severe male infertility, adenomyosis and endometriosis.

RESULTS

The first trimester pregnancy loss rate was 18.2% (693/ 3805). The presence of RPL increased first trimester pregnancy loss (OR = 7.729, 95%CI = 5.908-10.142, P = 0.000). BMI, which is > 30, increased first trimester pregnancy loss compared to < 25 (OR = 1.418, 95%CI = 1.025-1.950, P = 0.033). Endometrial preparation with artificial cycle increased first trimester pregnancy loss compared to natural cycle (OR = 2.101, 95%CI = 1.630-2.723, P = 0.000). Female age, which is 35-37, increased first trimester pregnancy loss compared to < 30 (OR = 1.617, 95%CI = 1.120-2.316, P = 0.018), and female age, which is > 37, increased first trimester pregnancy loss compared to < 30 (OR = 2.286, 95%CI = 1.146-4,38, P = 0.016). The presence of PCOS increased first trimester pregnancy loss (OR = 1.693, 95%CI = 1.198-2.390, P = 0.002). The number of previous IVF cycles, which is > 3, increased first trimester pregnancy loss compared to < 3 (OR = 2.182, 95%CI = 1.708-2.790, P = 0.000).

CONCLUSIONS

History of RPL, RIF, advanced female age, presence of PCOS, and high BMI (> 30 kg/m2) were the factors that increased first trimester pregnancy loss.

Age- and endometrial microbiota-related delay in development of endometrial receptivity

Purpose

We evaluated factors affecting the development of endometrial receptivity according to age and changes in the endometrial microbiota.

Methods

We recruited patients with infertility who underwent transcriptomic analyses of endometrial receptivity and the endometrial microbiome prior to frozen embryo transfer. An endometrial biopsy was performed 108 h after initial progesterone administration.

Results

In 185 tests from 185 eligible patients, the results of endometrial receptivity analysis were receptive in 111 (60.0%) patients and pre-receptive in 74 (40.0%) patients. Compared with receptive patients, pre-receptive patients had significantly older ages (36.0 ± 0.5 vs. 38.2 ± 0.5, p = 0.0021), a smaller proportion of normal Lactobacillus-dominant microbiota (27.9% vs. 12.2%), and a greater proportion of microbiota with ultralow biomass (22.5% vs. 41.9%) (p = 0.0074). Patient age (adjusted odds ratio: 1.08, 95% confidence interval: 1.01-1.16, p = 0.0351) and a microbiome with ultralow biomass (adjusted odds ratio: 3.82, 95% confidence interval: 1.49-9.82, p = 0.0039) were independent predictive factors for pre-receptive endometrium.

Conclusions

Older age was accompanied by a decrease in Lactobacillus-dominant microbiota; aging and endometrial microbiota with ultralow biomass were significantly associated with pre-receptive endometrium. Our findings suggest that the quantity (rather than proportion) of Lactobacillus in the endometrium is important in the development of endometrial receptivity.

Effect of BMI on the value of serum progesterone to predict clinical pregnancy outcome in IVF/ICSI cycles: a retrospective cohort study

Background

Numerous research have investigated the predictor role of progesterone (P) level on the human Chorionic Gonadotropin (hCG) trigger day of assisted reproductive technology (ART) outcomes. However, the relationship of progesterone levels on hCG day to clinical pregnancy outcomes in IVF/ICSI cycles for patients with different BMI groups is still elusive. This study aimed to investigate the effects of progesterone elevation on triggering day on clinical pregnancy rate (CPR) of IVF/ICSI cycles in patients with different female BMI.

Methods

We conducted a retrospective cohort study included 6982 normal-weight parents (18.5Kg/m2≤BMI<25Kg/m2) and 2628 overweight/obese patients (BMI≥25Kg/m2) who underwent fresh day 3 cleavage embryo transfer (ET) in IVF/ICSI cycles utilizing GnRH agonist to control ovarian stimulation.

Results

The interaction between BMI and P level on triggering day on CPRs was significant (p<0.001). The average level of serum P was reduced with the increase in maternal BMI. Serum P adversely affected CPR in distinct BMI groups. In the normal weight group, CPRs were decreasedas serum P concentrations gradually increased (p<0.001 for overall trend). The CPRs (lower than 65.8%) of progesterone level > 1.00 ng/ml on triggering day were significantly lower than that (72.4%) of progesterone level <0.5 ng/ml. In the overweight/obese group, CPRs showed a decrease statistically with progesterone levels of ≥2.00 ng/ml compared to progesterone levels of <0.5 ng/ml (51.0% VS. 64.9%, p=0.016). After adjusting for confounders, progesterone elevation (PE) negatively correlated with CPRs only in the normal weight group (OR: 0.755 [0.677-0.841], p<0.001), not in the overweight/obese group (p=0.063).

Conclusion

Women with higher BMI exhibited a lower progesterone level on triggering day. Additionally, PE on hCG day is related to decreased CPRs in GnRH agonist IVF/ICSI cycles with cleavage embryo transfers regardless of women's BMI level (normal weight VS. overweight/obesity).

Does the risk of embryo abnormality increase in PCOS women? A secondary analysis of a multi-center randomized controlled trial

CONTEXT

Some studies reported the early miscarriage rate was higher in PCOS women. However, whether the risk of embryo abnormalities increases in PCOS women is lack of evidence.

OBJECTIVE

To evaluate the association between polycystic ovarian syndrome (PCOS) and embryo ploidy.

DESIGN

A secondary analysis of multi-center randomized controlled trial which was conducted from July 2017 to June 2018. The original intent was to identify whether preimplantation genetic test for aneuploidy (PGT-A) improves the live birth rate as compared with in-vitro fertilization (IVF).

SETTING

14 reproductive centers.

PATIENTS

190 patients diagnosed with PCOS and 1:1 age-matched non-PCOS patients were chosen from PGT-A group. A total of 380 patients with 1118 embryos were included in our study.

INTERVENTIONS

Women diagnosed with PCOS.

MAIN OUTCOME MEASURES

Embryonic aneuploidy and embryonic mosaic.

RESULTS

After adjusted for potential confounders, the rate of embryonic aneuploidy and embryonic mosaic in PCOS group were comparable with control group [embryonic aneuploid rate PCOS group: 14.0% vs control group: 18.3%, adjusted OR (95%CI): 0.78(0.54,1.12), P = 0.19; embryonic mosaic rate 10.9% vs 10.1%, adjusted OR (95%CI): 0.91(0.59,1.40), P = 0.66]. We further stratified PCOS women into four groups according to phenotype. The rate of aneuploid and mosaic embryos was comparable between each of PCOS phenotype and control group. There was still no significant difference of embryonic aneuploid and embryo mosaic rates within four phenotypes.

CONCLUSIONS

The risk of aneuploid and mosaic embryos was not increased in PCOS women. Thus, we suggests that the miscarriage rate arising from abnormal embryonic chromosomes could be similar between PCOS and non-PCOS women.

The Endometrial Transcriptome of Metabolic and Inflammatory Pathways During the Window of Implantation Is Deranged in Infertile Obese Polycystic Ovarian Syndrome Women

Introduction and Aim: Obese women with polycystic ovarian syndrome (PCOS) have a reduced rate of spontaneous conception even when their cycles are ovulatory. Endometrial receptivity is an important factor for poor implantation and increased miscarriage rates. Mechanisms in which both pathologies modify the endometrium are not fully clarified. The aim of our study was to compare the endometrial transcriptomic profiles between infertile obese PCOS (O-PCOS) women and infertile normal weight subjects during the window of implantation in ovulatory menstrual cycles. Methods: We conducted a prospective transcriptomic analysis of the endometrium using RNA sequencing. In this way, potential endometrial mechanisms leading to the poor reproductive outcome in O-PCOS patients could be characterized. Endometrial samples during days 21-23 of the menstrual cycle were collected from infertile O-PCOS women (n = 11) and normal weight controls (n = 10). Subgroups were defined according to the ovulatory/anovulatory status in the natural cycles, and O-PCOS women were grouped into the O-PCOS ovulatory (O-PCOS-ovul) subgroup. RNA isolation, sequencing with library reparation, and subsequent RNAseq data analysis were performed. Results: Infertile O-PCOS patients had 610 differentially expressed genes (DEGs), after adjustment for multiple comparisons with normal weight infertile controls, related to obesity (MXRA5 and ECM1), PCOS (ADAMTS19 and SLC18A2), and metabolism (VNN1 and PC). In the ovulatory subgroup, no DEGs were found, but significant differences in canonical pathways and the upstream regulator were revealed. According to functional and upstream analyses of ovulatory subgroup comparisons, the most important biological processes were related to inflammation (TNFR1 signaling), insulin signaling (insulin receptor signaling and PI3/AKT), fatty acid metabolism (stearate biosynthesis I and palmitate biosynthesis I), and lipotoxicity (unfolded protein response pathway). Conclusions: We demonstrated that endometrial transcription in ovulatory O-PCOS patients is deranged in comparison with the control ovulatory endometrium. The most important pathways of differentiation include metabolism and inflammation. These processes could also represent potential mechanisms for poor embryo implantation, which prevent the development of a successful pregnancy. ClinicalTrials.gov ID: NCT03353948.

BMI and miscarriage after IVF

PURPOSE OF REVIEW

To summarize recent findings related to the risk of miscarriage in women with elevated BMI undergoing IVF, and the mechanisms involved in said risk.

RECENT FINDINGS

Miscarriage rates are increased in overweight and obese women in both natural and assisted reproduction. Oocyte and embryo quality assessed according to classic morphological static parameters does not seem to be affected by excessive female body weight. Despite the initial lack of consensus between studies regarding embryo morphokinetics in obese women, blastocyst formation and quality have recently been shown to be similar across BMI groups, even in the case of euploid embryos. However, some metabolomic differences have been described in oocytes and embryos from obese women, thus pointing to a functional alteration. In women with elevated BMI, the percentage of aneuploid embryos is similar to that of normal weight women, and rates of miscarriage are higher, despite the transfer of euploid embryos. Therefore, the origin of the increased pregnancy loss rate after IVF in these women may be related to metabolomic, epigenetic or mitochondrial oocyte and embryo disturbances, or to the abnormal endocrine, metabolic and inflammatory uterine environment induced by obesity, which seems to be also responsible for other numerous complications during pregnancy and the in-utero fetal programming of postnatal diseases. A displacement of the window of implantation in obese women undergoing artificial endometrial preparation has recently been described and may be related to the poorer embryo implantation rates and increased risk of miscarriage observed following fresh and frozen embryo transfers with autologous oocytes, and with donated ova in recipients with extremely high BMI.

SUMMARY

Female obesity is related to poorer outcome in natural and assisted conception, including an increased risk of miscarriage. Embryo morphology, assessed by conventional methods or by morphokinetics, does not seem to be affected by excess weight, with similar blastocyst formation and quality than normal weight women reported in IVF cycles. Embryo aneuploidy is not increased, and higher miscarriages rates are seen after euploid embryo transfer in obese women. Disturbances of the uterus or its environment induced by female obesity seem to be the most likely cause of the increased risk of miscarriage, although metabolomic, epigenetic or mitochondrial oocyte and embryo dysfunction cannot be ruled out as cannot congenital anomalies. In the context of all the above, weight reduction before pregnancy should be advised in obese women trying to become pregnant.

Lipid metabolism and endometrial receptivity

BACKGROUND

Obesity has now been recognized as a high-risk factor for reproductive health. Although remarkable advancements have been made in ART, a considerable number of infertile obese women still suffer from serial implantation failure, despite the high quality of embryos transferred. Although obesity has long been known to exert various deleterious effects on female fertility, the underlying mechanisms, especially the roles of lipid metabolism in endometrial receptivity, remain largely elusive.

OBJECTIVE AND RATIONALE

This review summarizes current evidence on the impacts of several major lipids and lipid-derived mediators on the embryonic implantation process. Emerging methods for evaluating endometrial receptivity, for example transcriptomic and lipidomic analysis, are also discussed.

SEARCH METHODS

The PubMed and Embase databases were searched using the following keywords: (lipid or fatty acid or prostaglandin or phospholipid or sphingolipid or endocannabinoid or lysophosphatidic acid or cholesterol or progesterone or estrogen or transcriptomic or lipidomic or obesity or dyslipidemia or polycystic ovary syndrome) AND (endometrial receptivity or uterine receptivity or embryo implantation or assisted reproductive technology or in vitro fertilization or embryo transfer). A comprehensive literature search was performed on the roles of lipid-related metabolic pathways in embryo implantation published between January 1970 and March 2022. Only studies with original data and reviews published in English were included in this review. Additional information was obtained from references cited in the articles resulting from the literature search.

OUTCOMES

Recent studies have shown that a fatty acids-related pro-inflammatory response in the embryo-endometrium boundary facilitates pregnancy via mediation of prostaglandin signaling. Phospholipid-derived mediators, for example endocannabinoids, lysophosphatidic acid and sphingosine-1-phosphate, are associated with endometrial receptivity, embryo spacing and decidualization based on evidence from both animal and human studies. Progesterone and estrogen are two cholesterol-derived steroid hormones that synergistically mediate the structural and functional alterations in the uterus ready for blastocyst implantation. Variations in serum cholesterol profiles throughout the menstrual cycle imply a demand for steroidogenesis at the time of window of implantation (WOI). Since 2002, endometrial transcriptomic analysis has been serving as a diagnostic tool for WOI dating. Numerous genes that govern lipid homeostasis have been identified and, based on specific alterations of lipidomic signatures differentially expressed in WOI, lipidomic analysis of endometrial fluid provides a possibility for non-invasive diagnosis of lipids alterations during the WOI.

WIDER IMPLICATIONS

Given that lipid metabolic dysregulation potentially plays a role in infertility, a better understanding of lipid metabolism could have significant clinical implications for the diagnosis and treatment of female reproductive disorders.

The Clinical Efficacy of Personalized Embryo Transfer Guided by the Endometrial Receptivity Array/Analysis on IVF/ICSI Outcomes: A Systematic Review and Meta-Analysis

Objective: To assess the prevalence of displaced window of implantation (WOI) in infertile women, and the clinical utility of personalized embryo transfer (pET) guided by the endometrial receptivity array/analysis (ERA) on IVF/ICSI outcomes.

Methods: The protocol was registered at Prospero: CRD42020204237. We systematically searched all published English literature related to the prevalence of WOI displacement and ongoing pregnancy rate/live birth rate in the overall good-prognosis infertile patients (GPP) and/or repeated implantation failure (RIF) patients undergoing IVF/ICSI-ET cycles after ERA test until August 2021.

Result(s): 11 published studies were enrolled in the final analysis. The estimate of the incidence of WOI displacement based on ERA was 38% (95%CI 19–57%) in GPP and 34% (95%CI 24–43%) in RIF, respectively. There was no difference in OPR/LBR between patients undergoing routine ET without ERA test and those who following pET with ERA (39.5 vs. 53.7%, OR 1.28, p = 0.49, 95%CI 0.92–1.77, I² = 0%) in relative GPP. Notably, the meta-analysis revealed that OPR/LBR of patients with RIF undergoing pET who had non-receptive ERA increased to the level of to those undergoing sET with receptive ERA (40.7 vs.49.6%, OR 0.94, p = 0.85, 95%CI 0.70–1.26, I² = 0%).

Conclusion: Considering the approximately one third of infertile women could suffered from displaced WOI, the ERA test emerged as a promising tool. Although the present meta-analysis demonstrates that patients with general good-prognosis may not benefit from ERA, pET guided by ERA significantly increases the chances of pregnancy for non-receptive patients with RIF of endometrial origin.

Effect of Female and Male Body Mass Index on Cumulative Live Birth Rates in the Freeze-all Strategy

CONTEXT

The impact of parental overweight/obese on cumulative live birth rate in in vitro fertilization/intracytoplasmic sperm injection using a freeze-all strategy is still unknown.

OBJECTIVE

To explore the effect of parental body mass index (BMI) on cumulative live birth rate (CLBR) in a freeze-all strategy over 1.5 years.

METHODS

This was a retrospective study in a tertiary care academic medical center; 23 482 patients (35 289 frozen-thawed embryo transfer cycles) were divided into 4 groups according to Asian BMI classification. The main outcome measure was CLBR.

RESULTS

Female overweight/obesity had a lower tendency in CLBR (groups 1-4: optimistic: 69.4%, 67.9%, 62.3%, and 65.7%; conservative: 62.9%, 61.1%, 55.4%, and 57.6%) and prolonged time (groups 1-4: 11.0, 12.2, 15.9, and 13.8 months for 60% CLBR in the optimistic method; 8.7, 9.5, 11.7, 11.0 months for 50% CLBR in the conservative method). The same trend to a lesser extent was also observed in male BMI groups. When combining parental BMI, "parental overweight/obesity" had lower CLBR and longer time for reaching CLBR >50% (optimistic: 4.5 months for 60% CLBR; conservative: 3 months for 50% CLBR), followed by "only female high BMI" (optimistic: 2.1 months for 60% CLBR; conservative: 1.7 months for 50% CLBR), while "only male high BMI" had no influence.

CONCLUSION

Our results showed the importance of parental BMI, female BMI, and male BMI on the 1.5-year CLBR using a freeze-all strategy; the time to reach the CLBR (60% in optimistic, 50% in conservative) for overweight and obese patients was several months, but it is not as long as losing weight.

Impact of obesity on medically assisted reproductive treatments

Increasing evidence has demonstrated that obesity impairs female fertility and negatively affects human reproductive outcome following medically assisted reproduction (MAR) treatment. In the United States, 36.5% of women of reproductive age are obese. Obesity results not only in metabolic disorders including type II diabetes and cardiovascular disease, but might also be responsible for chronic inflammation and oxidative stress. Several studies have demonstrated that inflammation and reactive oxygen species (ROS) in the ovary modify steroidogenesis and might induce anovulation, as well as affecting oocyte meiotic maturation, leading to impaired oocyte quality and embryo developmental competence. Although the adverse effect of female obesity on human reproduction has been an object of debate in the past, there is growing evidence showing a link between female obesity and increased risk of infertility. However, further studies need to clarify some gaps in knowledge. We reviewed the recent evidence on the association between female obesity and infertility. In particular, we highlight the association between fat distribution and reproductive outcome, and how the inflammation and oxidative stress mechanisms might reduce ovarian function and oocyte quality. Finally, we evaluate the connection between female obesity and endometrial receptivity.

Impact of metabolic disorders on endometrial receptivity in patients with polycystic ovary syndrome

The present study investigated the expression of endometrial receptivity-related molecules in patients with polycystic ovary syndrome (PCOS) and different androgen status, insulin resistance (IR) levels, and body mass indexes (BMI) to identify the mechanism underlying their effects on pregnancy outcomes. The present study recruited 43 participants from November 2020 to January 2021, which were classified into five groups: i) Hyperandrogenemia (HA) combined with impaired glucose tolerance group (n=8); ii) HA combined with diabetes mellitus group (n=8); iii) HA combined with non-IR (NIR) group (n=10); iv) non-HA (NHA) androgen combined with IR group (n=8); and v) NHA combined with NIR group (n=9). In addition, according to their BMIs, patients were sub-grouped into lean/normal (n=27), overweight (n=8) or obese (n=8) groups. The mRNA expression levels of endometrial receptivity-related molecules were detected using reverse transcription-quantitative PCR. In addition, flow cytometry was used to determine the phenotype and percentage of uterine natural killer cells (uNK). According to the results, patients with PCOS and IR status, HA and obesity (BMI ≥24 kg/m²) demonstrated significantly decreased mRNA expression levels of adiponectin, adiponectin receptor (AdipoR)1, AdipoR2, adapter protein containing PH domain, PTB domain and leucine zipper motif 1, estrogen receptor (ER) α, ERβ, progesterone receptor (PR), IL-15, integrin β3 avβ3, and insulin-like growth factor binding protein-1, but increased mRNA expression levels of IL-6 and IL-8 compared with NHA + NIR group or lean/normal group, respectively. In addition, obese patients with PCOS demonstrated increased mRNA expression levels of PR compared with overweight patients. This suggested that insulin resistant status, HA, and obesity could alter the endometrial receptivity of patients with PCOS, which may explain poorer embryo implantation and pregnancy outcomes in clinics.

Maternal Blood-Based Protein Biomarkers in Relation to Abdominal Fat Distribution Measured by Ultrasound in Early Mid-Pregnancy

The objective of this study was to examine the associations of early mid-pregnancy ultrasound measured visceral and subcutaneous fat depths with blood-based protein biomarkers. This was a cross-sectional study including 201 pregnant women at Uppsala University Hospital, Sweden. The mean age of the women was 31.0 years, and 57.7% were nulliparous. Maternal visceral and subcutaneous fat depths were measured by ultrasound at the early second-trimester anomaly scan. A non-fasting blood sample was collected in conjunction with the second-trimester anomaly scan, and the Olink cardiovascular II panel was used to measure 92 blood-based protein biomarkers in the sample. Cross-sectional associations of visceral and subcutaneous fat depths with blood-based protein biomarkers were examined using Mann-Whitney U tests with false discovery rate adjustments. In addition, linear regression analyses adjusting for maternal age, parity, and early pregnancy body mass index were performed. The results showed differences in one biomarker between women with elevated (≥ 52 mm) versus normal (< 52 mm) visceral fat depth, and in three biomarkers between women with elevated (≥ 22 mm) versus normal (< 22 mm) subcutaneous fat depth. Hence, levels of blood-based protein biomarkers differ between pregnant women with dissimilar body fat distributions, which might reflect disparities in biological pathways.

Clinical relevance of a newly developed endometrial receptivity test for patients with recurrent implantation failure in Japan

Purpose

To assess the clinical efficacy of personalized embryo transfer (pET) guided by a new endometrial receptivity test, ERPeak^SM, in patients with recurrent implantation failure (RIF).

Methods

Recurrent implantation failure patients of all ages at two private Japanese clinics from April 2019 to June 2020 were retrospectively analyzed. The intervention group (n = 244) received pET in accordance with endometrial receptivity testing results and was compared to control group (n = 306) receiving standardized timing, non‐personalized embryo transfer (npET). In propensity score matching analysis, the clinical pregnancy rate (CPR) and live birth rate (LBR) were compared between groups, and a subanalysis of advanced maternal age (AMA) (≥38 years old) versus non‐AMA (<38 years old) patients was also conducted.

Results

The CPR and LBR of the pET group were significantly higher than those of the npET group (37.7% vs. 20.0%, adjusted OR: 2.64; 95%CI, 1.70–4.11, p < 0.001 and 29.9% vs. 9.7%, adjusted OR: 4.13; 95%CI, 2.40–7.13, p < 0.001, respectively). Furthermore, in the subanalyses, the CPR and LBR of the pET group were significantly higher than those of the npET group in both the AMA non‐AMA patients.

Conclusions

The new ERPeak^SM endometrial receptivity test is a useful alternative diagnostic tool for poor‐prognosis patients, regardless of age.

Genetic Regulation of Transcription in the Endometrium in Health and Disease

The endometrium is a complex and dynamic tissue essential for fertility and implicated in many reproductive disorders. The tissue consists of glandular epithelium and vascularised stroma and is unique because it is constantly shed and regrown with each menstrual cycle, generating up to 10 mm of new mucosa. Consequently, there are marked changes in cell composition and gene expression across the menstrual cycle. Recent evidence shows expression of many genes is influenced by genetic variation between individuals. We and others have reported evidence for genetic effects on hundreds of genes in endometrium. The genetic factors influencing endometrial gene expression are highly correlated with the genetic effects on expression in other reproductive (e.g., in uterus and ovary) and digestive tissues (e.g., salivary gland and stomach), supporting a shared genetic regulation of gene expression in biologically similar tissues. There is also increasing evidence for cell specific genetic effects for some genes. Sample size for studies in endometrium are modest and results from the larger studies of gene expression in blood report genetic effects for a much higher proportion of genes than currently reported for endometrium. There is also emerging evidence for the importance of genetic variation on RNA splicing. Gene mapping studies for common disease, including diseases associated with endometrium, show most variation maps to intergenic regulatory regions. It is likely that genetic risk factors for disease function through modifying the program of cell specific gene expression. The emerging evidence from our gene mapping studies coupled with tissue specific studies, and the GTEx, eQTLGen and EpiMap projects, show we need to expand our understanding of the complex regulation of gene expression. These data also help to link disease genetic risk factors to specific target genes. Combining our data on genetic regulation of gene expression in endometrium, and cell types within the endometrium with gene mapping data for endometriosis and related diseases is beginning to uncover the specific genes and pathways responsible for increased risk of these diseases.

Blastocyst formation is similar in obese and normal weight women: a morphokinetic study

STUDY QUESTION

Does the embryo cleavage pattern and rate of blastocyst formation differ between normal weight and obese women undergoing IVF?

SUMMARY ANSWER

Embryo morphokinetic development, final blastocyst formation rate and blastocyst morphology do not differ between obese and normal weight women.

WHAT IS KNOWN ALREADY

Female obesity has been related to impaired IVF outcomes. Although the mechanisms responsible for this detrimental effect are thought to include impaired oocyte and embryo quality and reduced endometrial receptivity, they are yet to be confirmed. Embryo quality has been commonly assessed using static morphological criteria. Only three studies have analysed the progress of embryos up to the blastocyst stage in women with elevated BMI, but they have used small samples of patients or have obtained contradictory results.

STUDY DESIGN, SIZE, DURATION

This retrospective, cohort study, was performed from January 2016 to May 2020. A total of 3316 ICSI cycles from 2822 women were included, of which 1251 cycles were part of a preimplantation genetic testing programme. In total, 17 848 embryos were analysed.

PARTICIPANTS/MATERIALS, SETTING, METHODS

This study reports on the IVF cycles of infertile women, with a known BMI, who underwent ICSI and whose embryos were grown until the fifth/sixth day of development in a time-lapse system. Patients were grouped as follows. Underweight was defined as a BMI <18.5 kg/m2; normal weight was a BMI of 18.5-24.9 kg/m2; overweight was a BMI of 25-29.9 kg/m2; and obesity was a BMI of ≥30 kg/m2. Embryo development was assessed on an external computer with analysis software.

MAIN RESULTS AND THE ROLE OF CHANCE

Despite an initial slower pattern of embryo development, the blastocyst formation rate on day 5 or on day 5 plus day 6 did not differ in obese women with respect to the other three BMI groups. Moreover, based on the evaluation of inner cell mass and the trophectoderm on both days of blastocyst development, embryo quality was similar across the BMI groups, as were the pattern of development and arrest up to blastocyst formation and the distribution of the categories of full, expanded and hatching blastocysts.

LIMITATIONS, REASONS FOR CAUTION

Limitations include the retrospective analysis of data, the use of BMI as the only parameter to define normal/abnormal female body weight, and the lack of complete information about clinical outcomes.

WIDER IMPLICATIONS OF THE FINDINGS

Blastocyst formation and embryo morphokinetics are not affected by female obesity, and the poorer IVF outcomes described for such women are probably due to deficient endometrial receptivity. The role of endometrial progesterone exposure on the day of embryo transfer should be analysed in future studies as a possible determining factor.

STUDY FUNDING/COMPETING INTEREST(S)

No external funding was used and there are no competing interests.

TRIAL REGISTRATION NUMBER

N/A.

A review of the pathophysiology of recurrent implantation failure

Implantation is a critical step in human reproduction. The success of this step is dependent on a competent blastocyst, receptive endometrium, and successful cross talk between the embryonic and maternal interfaces. Recurrent implantation failure is the lack of implantation after the transfer of several embryo transfers. As the success of in vitro fertilization has increased and failures have become more unacceptable for patients and providers, the literature on recurrent implantation failure has increased. While this clinical phenomenon is often encountered, there is not a universally agreed-on definition-something addressed in an earlier portion of this Views and Reviews. Implantation failure can result from several different factors. In this review, we discuss factors including the maternal immune system, genetics of the embryo and parents, anatomic factors, hematologic factors, reproductive tract microbiome, and endocrine milieu, which factors into embryo and endometrial synchrony. These potential causes are at various stages of research and not all have clear implications or immediately apparent treatment.

[Overweight or obesity: impact on the results of the first IVF/ICSI attempt]

OBJECTIVES

To evaluate the influence of overweight and obesity on the results of the first in vitro fertilization attempt, without or with intracytoplasmic microinjection (IVF/ICSI), in terms of live births.

METHODS

Retrospective observational study concerning the first IVF/ICSI attempts from 01/01/2006 to 31/12/2017 carried out at the Assisted Reproductive Technology of the CHU of Besançon, studying the delivery rate (excluding frozen embryos transfers), and the data of Assisted Reproductive Technology attempts, in overweight (BMI 25 to 29.9kg/m²) and obese women (BMI≥30kg/m²), compared to women with a standard BMI (18 to 24.9kg/m²).

RESULTS

A total of 3192 patients were included. At the end of their first IVF/ICSI attempt, the delivery rate of women with standard BMI was 34.7%. The delivery rate was significantly lower in overweight women (29.5%, p=0.011) and comparable in obese women (32.4%, p=0.476). The birth rate of women with a BMI≥25 kg/m² was also significantly lower than that of women with a standard BMI (30.4% versus 34.7%, p=0.019). After multivariate analysis, the delivery rate in overweight patients remained significantly lower compared to the population with standard BMI (OR=0.707; 95% CI 0.561-0.890), and comparable in obese patients (OR=0.796; 95% CI 0.585-1.084).

CONCLUSION

The delivery rate was lower in overweight women, whereas it was not significantly different in obese women.

The Disorders of Endometrial Receptivity in PCOS and Its Mechanisms

Polycystic ovary syndrome (PCOS) is a mysterious and complicated endocrine disease with the combination of metabolic, reproductive, psychological dysfunctions. Impaired endometrial receptivity and ovulation disorders/anovulation are both important causes of PCOS-related infertility. However, change in endometrium has never received the same attention as ovulatory dysfunction. Besides, putting emphasis on endometrial function may be more realistic for PCOS-related infertility, given the wide use of assisted reproductive technology. The present review focuses on the disorders of endometrial receptivity of patients with PCOS, summarizes the changes of the indicators of endometrial receptivity including leukemia inhibitory factor, homeobox genes A, pinopodes, αvβ3-integrin, and intercellular junctions and also analyzes the possible mechanisms of decreased endometrial receptivity and its relationship with the main endocrine and metabolic disorders of PCOS such as hyperandrogenism, inflammation, insulin resistance, and obesity. Despite several biomarkers have been found to be associated with decreased endometrial receptivity in PCOS, the clinical relevance of these findings still awaits future clarification.

Obesity Affects Endometrial Receptivity by Displacing the Window of Implantation

Our aim was to determine prospectively whether increased body mass index (BMI) affects endometrial receptivity through displacement of the window of implantation (dWOI) using the endometrial receptivity analysis (ERA), and whether this effect is BMI-dependent. We recruited a population of 170 infertile women with a normal uterus and no clinical history of recurrent miscarriage or implantation failure. These women were divided into four groups according to BMI: normal weight (18.5-24.9 kg/m²; n = 44), overweight (25-29.9 kg/m²; n = 29), class I obese (30.0-34.9 kg/m²; n = 54), and class II and III obese (> 35 kg/m²; n = 43). We also assigned the patients to one of two larger BMI cohorts: non-obese (normal weight and overweight; n = 73) and obese (class I, II, and III obese; n = 97). We compared analytical and clinical data and dWOI in these categories, finding significant metabolic differences in glycemia, TSH, insulin, HDL cholesterol, LDL cholesterol, triglycerides, and systolic and diastolic blood pressure among the different BMI groups. One-day dWOI increased significantly with BMI, and significant differences were observed in the non-obese versus obese categories (9.7% vs 25.3 %, respectively (p = 0.02)). dWOI was most pronounced in patients with class II-III obesity. In addition, displacement was longer as BMI increased since ERA revealed a higher proportion of displacements of 1 day than of 12 h and showed they were predominantly pre-receptive. In conclusion, obesity has a negative effect on endometrial receptivity through delaying of the WOI, which increases in function of BMI as well as the metabolic disturbances of the patient.

Endometrial Receptivity Analysis (ERA): data versus opinions

This article summarises and contextualises the accumulated basic and clinical data on the ERA test and addresses specific comments and opinions presented by the opponent as part of an invited debate. Progress in medicine depends on new technologies and concepts that translate to practice to solve long-standing problems. In a key example, combining RNA sequencing data (transcriptomics) with artificial intelligence (AI) led to a clinical revolution in personalising disease diagnosis and fostered the concept of precision medicine. The reproductive field is no exception. Translation of endometrial transcriptomics to the clinic yielded an objective definition of the limited time period during which the maternal endometrium is receptive to an embryo, known as the window of implantation (WOI). The WOI is induced by the presence of exogenous and/or endogenous progesterone (P) after proper oestradiol (E2) priming. The window lasts 30-36 hours and, depending on the patient, occurs between LH + 6 and LH + 9 in natural cycles or between P + 4 and P + 7 in hormonal replacement therapy (HRT) cycles. In approximately 30% of IVF cycles in which embryo transfer is performed blindly, the WOI is displaced and embryo-endometrial synchrony is not achieved. Extending this application of endometrial transcriptomics, the endometrial receptivity analysis (ERA) test couples next-generation sequencing (NGS) to a computational predictor to identify transcriptomic signatures for each endometrial stage: proliferative (PRO), pre-receptive (PRE), receptive (R) and post-receptive (POST). In this way, personalised embryo transfer (pET) may be possible by synchronising embryo transfer with each patient's WOI. Data are the only way to confront arguments sustained in opinions and/or misleading concepts; it is up to the reader to make their own conclusions regarding its clinical utility.

Obesity and IVF: weighing in on the evidence

Obesity is associated with serious health risks, and its rising prevalence represents a growing public health emergency. Ongoing research into the association of obesity and assisted reproductive technology (ART) outcomes aims to disentangle selective detrimental effects of obesity on the oocyte and the endometrium. More translational studies involving women with severe obesity and in the third-party reproduction setting will help improve the standard of care in the provision of ART services for obese patients.

Routine endometrial receptivity array in first embryo transfer cycles does not improve live birth rate

OBJECTIVE

To compare the live birth rate between patients who undergo personalized embryo transfer (pET) after endometrial receptivity array (ERA) versus frozen embryo transfer (FET) with standard timing in first single euploid FET cycles. To report the rate of displacement of the window of implantation (WOI) in an infertile population without a history of implantation failure.

DESIGN

Prospective cohort study of patients who underwent their first single euploid programmed FET.

SETTING

Private fertility clinic.

PATIENT(S)

Patients who underwent first autologous single euploid programmed FET between January 2018 and April 2019.

INTERVENTION(S)

Endometrial biopsy with ERA followed by pET as indicated.

MAIN OUTCOME MEASURE(S)

Live birth rate and rate of receptive and nonreceptive ERA.

RESULT(S)

A total of 228 single euploid FET cycles were included in our analysis. Of those, 147 (64.5%) were ERA/pET cycles, and 81 (35.5%) were standard timing FET cycles. Endometrial receptivity array was receptive in 60/147 (40.8%) and nonreceptive in 87/147 (59.2%) patients. Nonreceptive ERAs were prereceptive in 93.1% of cases. The live birth rate did not differ between patients who underwent FET with standard timing and patients who underwent ERA/pET, 45/81 (56.6%) and 83/147 (56.5%), respectively.

CONCLUSION(S)

Our data do not support the routine use of ERA in an unselected patient population undergoing first autologous single euploid programmed embryo transfer.

Female obesity increases the risk of miscarriage of euploid embryos

OBJECTIVE

To determine whether female body mass index (BMI) is associated with an increased risk of miscarriage after euploid embryo transfer.

DESIGN

A retrospective, observational, multicenter cohort study.

SETTING

University-affiliated in vitro fertilization center.

PATIENT(S)

In this study, 3,480 cycles of in vitro fertilization with preimplantation genetic testing for aneuploidy (PGT-A) in the blastocyst stage and euploid embryo transfer were divided into four groups according to patient BMI.

INTERVENTION(S)

In vitro fertilization with PGT-A.

MAIN OUTCOME MEASURE(S)

The primary outcome was the miscarriage rate, which included both biochemical and clinical miscarriages. Secondary outcomes were implantation, pregnancy, clinical pregnancy, and live birth rates.

RESULT(S)

Cycles were divided into four groups according to BMI (kg/m²): underweight (<18.5; n = 155), normal weight (18.5-24.9; n = 2,549), overweight (25-29.9; n = 591), and obese (≥30; n = 185). The number of PGT-A cycles per patient was similar in the four groups. Fertilization rate, day of embryo biopsy, technique of chromosomal analysis, number of euploid embryos, number of transferred embryos, and method of endometrial preparation for embryo transfer were similar in the four BMI groups. Miscarriage rates were significantly higher in women with obesity compared to women with normal weight, mainly due to a significant increase in the clinical miscarriage rates. Live birth rates also were lower in women with obesity. Obesity in women and day 6 trophectoderm biopsy were found to influence the reduced live birth rate.

CONCLUSION(S)

Women with obesity experience a higher rate of miscarriage after euploid embryo transfer than women with a normal weight, suggesting that other mechanisms than aneuploidy are responsible for this outcome.

The association of euploid miscarriage with obesity

Objective

To determine whether the frequency of euploid miscarriage is increased in obese women with early pregnancy loss.

Design

Retrospective cohort study.

Setting

Academic medical center.

Patient(s)

A total of 2,620 women with cytogenetic analysis results from products of conception after a pregnancy loss <20 weeks gestation from 2006–2018.

Intervention(s)

None.

Main Outcome Measure(s)

Frequency of euploid miscarriage was compared in obese (body mass index [BMI] ≥30 kg/m²) versus non-obese (BMI <30 kg/m²) patients.

Result(s)

A total of 2,620 women with a mean (± standard deviation) age at time of loss of 34.9 years (± 4.9) and mean (± standard deviation) BMI of 25.3 kg/m² (±5.5) were included in the final analysis. After adjusting for age and race, obese women were 56% more likely to have a euploid pregnancy loss compared with nonobese women (odds ratio 1.56; 95% confidence interval 1.32–1.92). Within the cohort, 63.8% of the losses were aneuploid, of which 41% were trisomies, 8% were monosomies, and 7% were polyploidies. Of the euploid losses, 50.1% were 46,XX and 49.9% were 46,XY, which suggests that the rate of maternal cell contamination was low.

Conclusion(s)

Obese women have an increased frequency of euploid miscarriage when compared with nonobese women.

Advanced glycation end products present in the obese uterine environment compromise preimplantation embryo development

RESEARCH QUESTION

Proinflammatory advanced glycation end products (AGE), highly elevated within the uterine cavity of obese women, compromise endometrial function. Do AGE also impact preimplantation embryo development and function?

DESIGN

Mouse embryos were cultured in AGE equimolar to uterine fluid concentrations in lean (1-2 µmol/l) or obese (4-8 µmol/l) women. Differential nuclear staining identified cell allocation to inner cell mass (ICM) and trophectoderm (TE) (day 4 and 5 of culture). Cell apoptosis was examined by terminal deoxynucleotidyl transferase-mediated dUDP nick-end labelling assay (day 5). Day 4 embryos were placed on bovine serum albumin/fibronectin-coated plates and embryo outgrowth assessed 93 h later as a marker of implantation potential. AGE effects on cell lineage allocation were reassessed following pharmacological interventions: either 12.5 nmol/l AGE receptor (RAGE) antagonist; 0.1 nmol/l metformin; or combination of 10 µmol/l acetyl-l-carnitine, 10 µmol/l N-acetyl-l-cysteine, and 5 µmol/l alpha-lipoic acid.

RESULTS

8 µmol/l AGE reduced: hatching rates (day 5, P < 0.01); total cell number (days 4, 5, P < 0.01); TE cell number (day 5, P < 0.01), and embryo outgrowth (P < 0.01). RAGE antagonism improved day 5 TE cell number.

CONCLUSIONS

AGE equimolar with the obese uterine environment detrimentally impact preimplantation embryo development. In natural cycles, prolonged exposure to AGE may developmentally compromise embryos, whereas following assisted reproductive technology cycles, placement of a high-quality embryo into an adverse 'high AGE' environment may impede implantation success. The modest impact of short-term RAGE antagonism on improving embryo outcomes indicates preconception AGE reduction via pharmacological or dietary intervention may improve reproductive outcomes for overweight/obese women.

Endometrial receptivity and pregnancy outcome

Human implantation is a highly complex and multifactorial process. Successful implantation requires the presence of a healthy embryo, a receptive endometrium, and a synchronized molecular dialogue between the two, as well as immune tolerance/protection from the host. The endometrial receptivity refers to a hormonally limited period in which the endometrial tissue acquires a transient functional status allowing blastocyst implantation and pregnancy initiation. Global knowledge of endometrial receptivity grew up in recent years. Improvements in genetics, new biomarkers, noninvasive methods, new advanced techniques (Endometrial receptivity assay - the ERA system, proteomic analysis) offer the possibility to evaluate the endometrial status and to manage patients with infertility problems, especially women undergoing assisted reproductive treatment. This overview reports the most relevant knowledge and recent advances in the study of implantation processes from the perspective of the endometrium, often considered as being the main barrier for a successful pregnancy initiation. Endometrial receptivity is a topic of great interest and further studies are needed for the early identification of endometrial abnormalities and the discovery of new strategies for increasing the chance for the establishment of pregnancy.

Obesity does not alter endometrial gene expression in women with endometriosis

RESEARCH QUESTION

Does obesity affect endometrial gene expression in women with endometriosis, specifically women with stage I disease?

DESIGN

Differential gene expression analysis was conducted on endometrium from women with and without endometriosis (n = 169). Women were diagnosed after surgical visualization and staged according to the revised American Society for Reproductive Medicine (stage I-IV). Women were grouped by body mass index (BMI) (kg/m²) as underweight, normal, pre-obese or obese. After accounting for menstrual cycle stage, endometrial gene expression was analysed by BMI (continuous and grouped) in women with endometriosis, and in non-endometriosis controls.

RESULTS

No significant interaction effect was found between BMI and endometriosis status on endometrial gene expression. We have previously reported that obese women with endometriosis have a reduced incidence of stage I disease; however, stratifying our analysis into stage I endometriosis versus combined II, III and IV endometriosis failed to reveal any differentially expressed endometrial genes between normal, pre-obese and obese patients.

CONCLUSIONS

Despite obesity having deleterious effects on endometrial gene expression in other gynaecological pathologies, e.g. endometrial cancer and polycystic ovary syndrome, our results do not support an association between BMI and altered endometrial gene expression in women with or without endometriosis.

Effect of body mass index on pregnancy outcomes in a freeze-all policy: an analysis of 22,043 first autologous frozen-thawed embryo transfer cycles in China

BACKGROUND

Abnormal BMI is associated with discouraging IVF outcomes in fresh autologous or oocyte donor cycles, whether or not such a relation also holds true for women undergoing frozen-thawed embryo transfer (FET) remains unknown. In addition, it remains unclear the detrimental effect of abnormal BMI on IVF outcomes occurs at the level of ovary or endometrium.

METHODS

A retrospective study involved 22,043 first FET cycles of all women who had undergone a freeze-all policy during the period from January 2010 to June 2017. To control for the embryo factor, our analysis was restricted to women with high-quality embryo transfer. The main outcome measure was live birth rate per embryo transfer. The secondary endpoints included rates of implantation, clinical pregnancy, multiple pregnancy, and pregnancy loss. Multivariate logistic regression analysis was performed to detect the independent effect of BMI on live birth rate after adjusting for important confounding variables.

RESULTS

In the crude analysis, reproductive outcomes were similar between underweight women and normal-weight controls whereas all parameter outcomes were significantly worse in patients with obesity. After adjustment for a number of confounding factors, underweight women had a marginally significant decrease in rates of implantation (adjusted odds ratio (aOR) 0.91; 95% CI 0.85-0.96), clinical pregnancy (aOR 0.91; 95% CI 0.83-0.99), and live birth (aOR 0.91; 95% CI 0.83-0.99) as compared to the women with normal weight. Obesity was significantly associated with decreased implantation (aOR 0.80; 95% CI 0.73-0.87), clinical pregnancy (aOR 0.81; 95% CI 0.71-0.91), and live birth rates (aOR 0.70; 95% CI 0.62-0.80). Moreover, the pregnancy loss rate, both in the first (aOR 1.46; 95% CI 1.15-1.87) and in the second trimester (aOR 2.76; 95% CI 1.67-4.58), was significantly higher in the obesity group than that in the reference group.

CONCLUSIONS

Among women undergoing first FET with high-quality embryo transfer, low BMI has limited impact on pregnancy and live birth rates. On the contrary, obesity was associated with worse IVF outcomes. Our findings further highlighted that endometrial receptivity played an important role in the poor reproductive outcomes of women with abnormal weight status.

Obesity alters the uterine environment before pregnancy

Obesity is a metabolic disorder that predisposes to numerous diseases and has become a major global public health concern. Cafeteria diet (CAF) is the animal model used for the study of obesity that more closely reflects Western diet habits. Previously, we described that CAF administration for 60 days induces obesity in female rats and their fetuses develop macrosomia. Given that, in our model, rats are not genetically modified and that obese mothers were fed standard chow during pregnancy, the aim of the current study was to test the hypothesis that obesity alters the intrauterine environment prior to pregnancy, and this may explain the exacerbated fetal weight gain. We found that uteri from obese rats during the estrous phase developed insulin resistance through mechanisms that involve the induction of uterine hypoxia and the down-regulation of the insulin receptor gene. Moreover, uterine cell proliferation was induced by obesity concomitantly with the reduction in the uterine contractile response to a β2 AR agonist, salbutamol, and this may be consequence of the down-regulation in the uterine β2 AR expression. We conclude that CAF-induced obesity alters the uterine environment in rats during the estrous phase and may cause the fetal macrosomia previously described by us in obese animals. The lower sensitivity of the uterus to a relaxation stimulus (salbutamol) is not a minor fact given that for implantation to occur the uterus must be relaxed for embryo nidation. Thus, the alteration in the uterine quiescence may impair implantation and, consequently, the foregoing pregnancy.

Depot-specific inflammation with decreased expression of ATM2 in white adipose tissues induced by high-margarine/lard intake

A high-fat diet has been recognized as an important risk factor of obesity, with variable impacts of different fatty acid compositions on the physiological process. To understand the effects of a high-margarine/lard diet, which is a major source of trans fatty acids (TFAs)/ saturated fatty acids (SFAs), elaidic acid as a biomarker of margarine intake was used to screen affected adipokines on mature human adipocytes in vitro. Weaned male Wistar rats were fed a high-fat diet enriched with margarine/lard to generate obesity-prone (OP) and obesity-resistant (OR) models, which were then used to explore the inflammatory responses of depot-specific white adipose tissue. Adiposity, glucose and lipid metabolism parameters and macrophage cell markers were also compared in vivo. In the subcutaneous depot, a high-margarine diet induced elevated IL-6, MCP-1 and XCL1 expression levels in both M-OP and M-OR groups. High-lard diet-fed rats displayed higher protein expression levels of MCP-1 and XCL1 compared with the control group. In the epididymal depot, significantly elevated IL-6 production was observed in M-OP rats, and high-lard diet-fed rats displayed elevated IL-6 and decreased XCL1 expression. In the retroperitoneal depot, a high-margarine diet caused higher IL-6 and MCP-1 expression levels, a high-lard diet caused elevated IL-6 expression in L-OP/L-OR rats, and elevated XCL1 expression was observed only in L-OP rats. In general, CD206 mRNA levels were notably down-regulated by high-fat diet feeding in the above-mentioned depots. CD11c mRNA levels were slightly upregulated in the subcutaneous depot of OP rats fed a high-margarine/lard diet. In the epidydimal depot, higher expression levels of F4/80 and CD206 mRNA were observed only in high-margarine diet-fed OP rats. These results suggest that depot-specific inflammation with decreased expression of adipose tissue anti-inflammatory M2-type (ATM2) macrophages could be induced by high-margarine/lard intake.

Obesity results with smaller oocyte in in vitro fertilization/intracytoplasmic sperm injection cycles-a prospective study

BACKGROUND

Obesity is associated with several fertility disorders. This prospective cohort study was designed to evaluate the effect of body mass index (BMI) (kg/m2) on oocyte diameter and treatment.

METHODS

Women undergoing in vitro fertilization (IVF) with intracytoplasmic sperm injection (ICSI) were enrolled in the study. They were divided into two groups according to BMI: obese (BMI > 30) and normal weight (BMI < 25). Mature oocytes were evaluated according to total diameter, zona pellucida, and oolema diameters.

RESULTS

A total of 387 oocytes were obtained from the 46 women who participated. Significantly more mature oocytes (M2) were retrieved from normal weight patients compare to obese women (15.1 ± 6.8 vs. 9.7 ± 3.9, respectively, P < 0.001). Oocytes from women in the obese group were significantly smaller than those in the normal weight group, including oocyte diameter (157.9 ± 7.9 vs. 164.3 ± 5.1 μm, P < 0.0001), oolema diameter (110.3 ± 4.5 vs. 113.5 ± 3.5 μm, P < 0.0001), and zona pellucida thickness (17.9 ± 2.6 vs. 19.0 ± 2.4 μm, P < 0.000), respectively. Multivariate logistic regression analysis, including oolema diameter, female age, BMI, number of M2 oocytes, and zona pellucida, was conducted to predict pregnancy. Small oolema diameter in obese patient adversely correlated with pregnancy. Larger oolema diameter was positively associated with the probability of pregnancy in the obese group as well as thinner zona pellucida.

CONCLUSION

Obesity is associated with smaller oocytes, which adversely affect fertility outcomes.

TRIAL REGISTRATION

NIH number NCT01672931.