Naturally occurring horse model of miscarriage reveals temporal relationship between chromosomal aberration type and point of lethality.

Chromosomal abnormalities are a common cause of human miscarriage but rarely reported in any other species. As a result, there are currently inadequate animal models available to study this condition. Horses present one potential model since mares receive intense gynecological care. This allowed us to investigate the prevalence of chromosomal copy number aberrations in 256 products of conception (POC) in a naturally occurring model of pregnancy loss (PL). Triploidy (three haploid sets of chromosomes) was the most common aberration, found in 42% of POCs following PL over the embryonic period. Over the same period, trisomies and monosomies were identified in 11.6% of POCs and subchromosomal aberrations in 4.2%. Whole and subchromosomal aberrations involved 17 autosomes, with chromosomes 3, 4, and 20 having the highest number of aberrations. Triploid fetuses had clear gross developmental anomalies of the brain. Collectively, data demonstrate that alterations in chromosome number contribute to PL similarly in women and mares, with triploidy the dominant ploidy type over the key period of organogenesis. These findings, along with highly conserved synteny between human and horse chromosomes, similar gestation lengths, and the shared single greatest risk for PL being advancing maternal age, provide strong evidence for the first animal model to truly recapitulate many key features of human miscarriage arising due to chromosomal aberrations, with shared benefits for humans and equids.

X centromeric drive may explain the prevalence of polycystic ovary syndrome and other conditions: Genomic structure of the human X chromosome pericentromeric region is consistent with meiotic drive associated with PCOS and other conditions.

X chromosome centromeric drive may explain the prevalence of polycystic ovary syndrome and contribute to oocyte aneuploidy, menopause, and other conditions. The mammalian X chromosome may be vulnerable to meiotic drive because of X inactivation in the female germline. The human X pericentromeric region contains genes potentially involved in meiotic mechanisms, including multiple SPIN1 and ZXDC paralogs. This is consistent with a multigenic drive system comprising differential modification of the active and inactive X chromosome centromeres in female primordial germ cells and preferential segregation of the previously inactivated X chromosome centromere to the polar body at meiosis I. The drive mechanism may explain differences in X chromosome regulation in the female germlines of the human and mouse and, based on the functions encoded by the genes in the region, the transmission of X pericentromeric genetic or epigenetic variants to progeny could contribute to preeclampsia, autism, and differences in sexual differentiation.

Trophoblast PR-SET7 dysfunction induces viral mimicry response and necroptosis associated with recurrent miscarriage.

Recurrent miscarriage (RM) is a distressing pregnancy complication. While the etiology of RM remains unclear, growing evidence has indicated the relevance of trophoblast impairment to the pathogenesis of RM. PR-SET7 is the sole enzyme catalyzing monomethylation of H4K20 (H4K20me1) and has been implicated in many pathophysiological processes. However, how PR-SET7 functions in trophoblasts and its relevance to RM remain unknown. Here, we found that trophoblast-specific loss of Pr-set7 in mice led to defective trophoblasts, resulting in early embryonic loss. Mechanistic analysis revealed that PR-SET7 deficiency in trophoblasts derepressed endogenous retroviruses (ERVs), leading to double-stranded RNA stress and subsequent viral mimicry, which drove overwhelming interferon response and necroptosis. Further examination discovered that H4K20me1 and H4K20me3 mediated the inhibition of cell-intrinsic expression of ERVs. Importantly, dysregulation of PR-SET7 expression and the corresponding aberrant epigenetic modifications were observed in the placentas of RM. Collectively, our results demonstrate that PR-SET7 acts as an epigenetic transcriptional modulator essential for repressing ERVs in trophoblasts, ensuring normal pregnancy and fetal survival, which sheds new light on potential epigenetic causes contributing to RM.

The fetal lineage is susceptible to Zika virus infection within days of fertilization.

Adults contracting Zika virus (ZIKV) typically exhibit mild symptoms, yet ZIKV infection of pregnant individuals can cause miscarriage or birth defects in their offspring. Many studies have focused on maternal-to-fetal ZIKV transmission via blood and placenta. Notably, however, ZIKV is also transmitted sexually, raising the possibility that ZIKV could infect the embryo shortly after fertilization, long before the placenta is established. Here, we evaluate the consequences of ZIKV infection in mouse embryos during the first few days of embryogenesis. We show that divergent strains of ZIKV can infect the fetal lineage and can cause developmental arrest, raising concern for the developmental consequences of sexual ZIKV transmission. This article has an associated 'The people behind the papers' interview.

IL-2/JES6-1 antibody complex expands the maternal T regulatory cell pool and alleviates fetal loss in abortion-prone mice.

Regulatory T (Treg) cells are essential for immune tolerance of embryo implantation and insufficient Treg cells are implicated in early pregnancy loss. An abortion-prone mouse model was utilized to evaluate the utility of IL-2 complexed with JES6-1 anti-IL-2 antibody (IL-2/JES6-1) to boost uterine Treg cells and improve reproductive success. IL-2/JES6-1 but not IL-2/IgG control administered in the peri-conception phase to CBA/J females mated with DBA/2 males elicited a >2-fold increase in the proportion of CD4+ T cells expressing FOXP3, and an increase in the ratio of FOXP3+ Treg cells to FOXP3- T conventional cells, in the uterus and its draining lymph nodes at embryo implantation that was sustained into mid-gestation. An attenuated phenotype was evident in both thymic-derived and peripheral Treg cells with elevated CTLA4, CD25, and FOXP3 indicating improved suppressive function, as well as increased proliferative marker Ki67. IL-2/JES6-1 treatment reduced fetal loss from 31% to 10%, but this was accompanied by a 6% reduction in late gestation fetal weight, despite comparable placental size and architecture. Similar effects of IL-2/JES6-1 on Treg cells and fetal growth were seen in CBA/J females with healthy pregnancies sired by BALB/c males. These findings show that expanding the uterine Treg cell pool through targeting IL-2 signaling is a strategy worthy of further investigation for mitigating immune-mediated fetal loss.

ENO1 promotes trophoblast invasion regulated by E2F8 in recurrent miscarriage.

Recurrent miscarriage (RM) is related to the dysfunction of extravillous trophoblast cells (EVTs), but the comprehensive mechanisms remain largely unexplored. We analyzed single-cell RNA sequencing (scRNA-seq), bulk RNA sequencing and microarray datasets obtained from Gene Expression Omnibus (GEO) database to explore the hub genes in the mechanisms of RM. We identified 1724 differentially expressed genes (DEGs) in EVTs from the RM, and they were all expressed along the trajectory of EVTs. These DEGs were associated with hypoxia and glucose metabolism. Single-cell Regulatory Network Inference and Clustering (SCENIC) analysis revealed that E2F transcription factor (E2F) 8 (E2F8) was a key transcription factor for these DEGs. And the expression of ENO1 can be positively regulated by E2F8 via RNA sequencing analysis. Subsequently, we performed immunofluorescence assay (IF), plasmid transfection, western blotting, chromatin immunoprecipitation (ChIP), real-time quantitative polymerase chain reaction (qRT-PCR), and transwell assays for validation experiments. We found that the expression of alpha-Enolase 1 (ENO1) was lower in the placentas of RM. Importantly, E2F8 can transcriptionally regulate the expression of ENO1 to promote the invasion of trophoblast cells by inhibiting secreted frizzled-related protein 1/4 (SFRP1/4) to activate Wnt signaling pathway. Our results suggest that ENO1 can promote trophoblast invasion via an E2F8-dependent manner, highlighting a potential novel target for the physiological mechanisms of RM.

Anti-proliferation and apoptosis induced via the mTOR/PGC-1α signaling pathway in trophoblast cells of miscarriage.

Miscarriage is a common complication during early pregnancy and affects approximately 10%-15% of all pregnant women. Several studies have reported that the abnormal expression of mitochondrial oxidative stress-related genes might be involved in the occurrence and progression of miscarriage. The present study attempted to uncover the role of peroxisome proliferator-activated receptor gamma coactivator-1α (PGC-1α) in miscarriage chorionic villous tissue. The hypothesis that PGC-1α is crucial for glycolysis and oxidative phosphorylation during early pregnancy was tested. The results showed that the mRNA and protein levels of PGC-1α were significantly increased in the miscarriage chorionic villous tissues compared with the artificial selective abortion group, and that the expression was regulated by mTOR in knockdown and overexpression of mTOR in HTR8 cell lines. PGC-1α also promoted mitochondrion oxidative phosphorylation but inhibited glycolysis process. In addition, PGC-1α could drive ROS production, reduce mitochondrial membrane potential and block NADPH synthesis, resulting in cell cycle arrest and cell apoptosis, eventually leading to miscarriage. These results suggested that the aberrant expression of PGC-1α is involved in the etiology of early miscarriage, providing new perspectives regarding the mechanisms of miscarriage and a potential therapeutic target for miscarriage.

Maternal selection of human embryos in early gestation: Insights from recurrent miscarriage.

Compared to most mammals, human pregnancy is unusual in that it involves chromosomally diverse embryos, cyclical breakdown and regeneration of the uterine mucosa, and intimate integration of fetal and maternal cells at the uteroplacental interface. Not surprisingly, pregnancy often falters in early gestation. Whether these losses result in clinical miscarriages depends on the origins and impacts of chromosomal errors on fetal development and the ability of the decidualizing endometrium to engage in embryo biosensing and selection. Aneuploidy originating in oocytes during meiosis drives the age-related risk of miscarriage. By contrast, the frequency of endometrial cycles with an impaired decidual response may account for the stepwise increase in miscarriage rates with each pregnancy loss independently of maternal age. Additional physiological mechanisms operate in early gestation to ensure that most failing pregnancies are lost before vascular maternal-fetal connections are established by the end of the first trimester. Here, we summarise how investigations into the mechanisms that cause miscarriage led to new insights into the processes that govern maternal selection of human embryos in early gestation.

Pyroptosis is involved in the immune microenvironment regulation of unexplained recurrent miscarriage.

Unexplained recurrent miscarriage (URM) is a common pregnancy complication with few effective therapies. Moreover, little is known regarding the role of pyroptosis in the regulation of the URM immune microenvironment. To address this issue, gene expression profiles of publicly available placental datasets GSE22490 and GSE76862 were downloaded from the Gene Expression Omnibus database. Pyroptosis-related differentially expressed genes were identified and a total of 16 differentially expressed genes associated with pyroptosis were detected, among which 1 was upregulated and 15 were downregulated. Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses indicated that the functionally enriched modules and pathways of these genes are closely related to immune and inflammatory responses. Four hub genes were identified: BTK, TLR8, NLRC4, and TNFSF13B. BTK, TLR8, and TNFSF13B were highly connected with immune cells, according to the correlation analysis of four hub genes and 20 different types of immune cells (p < 0.05). The four hub genes were used as research objects to construct the interaction networks. Chorionic villus tissue was used for quantitative real-time polymerase chain reaction and western blot to confirm the expression levels of hub genes, and the results showed that the expression of the four hub genes was significantly decreased in the chorionic villus tissue in the URM group. Collectively, the present study indicates that perhaps pyroptosis is essential to the diversity and complexity of the URM immune microenvironment, and provides a theoretical basis and research ideas for subsequent target gene verification and mechanism research.

Cellular senescence in reproduction: a two-edged sword†.

Cellular senescence (CS) is the state when cells are no longer capable to divide even after stimulation with grown factors. Cells that begin to undergo CS stop in the cell cycle and enter a suspended state without committing to programmed cell death. These cells assume a specific phenotype and influence their microenvironment by secreting molecules and extracellular vesicles that are part of the so-called senescent cell-associated secretory phenotype (SASP). Cellular senescence is intertwined with physiological and pathological conditions in the human organism. In terms of reproduction, senescent cells are present from reproductive tissues and germ cells to gestational tissues, and participate from fertilization to delivery, going through adverse reproductive outcomes such as pregnancy losses. Furthermore, various SASP molecules are enriched in gestational tissues throughout pregnancy. Thus, the aim of this review is to provide a basis about the features and potential roles played by CS throughout the reproductive process, encompassing its implication in each step of it and proposing a way to manage it in adverse reproductive contexts.

Increased EHD1 in trophoblasts causes RSM by activating TGFß signaling.

BACKGROUND: Recurrent spontaneous miscarriage (RSM) is one of the complications during pregnancy. However, the pathogenesis of RSM is far from fully elucidated. OBJECTIVE: Since the endocytic pathway is crucial for cellular homeostasis, our study aimed to explore the roles of endocytic recycling, especially EH domain containing 1 (EHD1), a member of the endocytic recycling compartment, in RSM. STUDY DESIGN: We first investigated the expression of the endocytic pathway member EHD1 in villi from the normal and RSM groups. Then, we performed RNA sequencing and experiments in villi, HTR8 cells and BeWo cells to determine the mechanisms by which EHD1 induced RSM. Finally, placenta-specific EHD1-overexpressing mice were generated to investigate the RSM phenotype in vivo. RESULTS: EHD1 was expressed in extravillous trophoblasts (EVTs) and syncytiotrophoblast (STB) in the villi. Compared with the control group, RSM patients expressed higher EHD1. A high level of EHD1 decreased proliferation, promoted apoptosis, and reduced the migration and invasion of HTR8 cells by activating the TGFBR1-SMAD2/3 signaling pathway. The TGFBR1 antagonist LY3200882 partially reversed the EHD1 overexpression-induced changes in the cell phenotype. Besides, a high level of EHD1 also induced abnormal syncytialization, which disturbed maternal-fetal material exchanges. In a mouse model, placenta-specific overexpression of EHD1 led to the failure of spiral artery remodeling, excessive syncytialization and miscarriage. CONCLUSIONS: Increased expression of EHD1 impaired the invasion of EVTs mediated by the TGFBR1-SMAD2/3 signaling pathway and induced abnormal syncytialization of STB, which is at least partially responsible for RSM.

Deficiency of UCHL1 results in insufficient decidualization accompanied by impaired dNK modulation and eventually miscarriage.

BACKGROUND: Miscarriage is a frustrating complication of pregnancy that is common among women of reproductive age. Insufficient decidualization which not only impairs embryo implantation but disturbs fetomaternal immune-tolerance, has been widely regarded as a major cause of miscarriage; however, the underlying mechanisms resulting in decidual impairment are largely unknown. METHODS: With informed consent, decidual tissue from patients with spontaneous abortion or normal pregnant women was collected to detect the expression profile of UCHL1. Human endometrial stromal cells (HESCs) were used to explore the roles of UCHL1 in decidualization and dNK modulation, as well as the mechanisms involved. C57/BL6 female mice (7-10 weeks old) were used to construct pregnancy model or artificially induced decidualization model to evaluate the effect of UCHL1 on mice decidualization and pregnancy outcome. RESULTS: The Ubiquitin C-terminal hydrolase L1 (UCHL1), as a deubiquitinating enzyme, was significantly downregulated in decidua from patients with miscarriage, along with impaired decidualization and decreased dNKs. Blockage of UCHL1 led to insufficient decidualization and resultant decreased expression of cytokines CXCL12, IL-15, TGF-ß which were critical for generation of decidual NK cells (dNKs), whereas UCHL1 overexpression enhanced decidualization accompanied by increase in dNKs. Mechanistically, the promotion of UCHL1 on decidualization was dependent on its deubiquitinating activity, and intervention of UCHL1 inhibited the activation of JAK2/STAT3 signaling pathway, resulting in aberrant decidualization and decreased production of cytokines associated with dNKs modulation. Furthermore, we found that inhibition of UCHL1 also disrupted the decidualization in mice and eventually caused adverse pregnancy outcome. CONCLUSIONS: UCHL1 plays significant roles in decidualization and dNKs modulation during pregnancy in both humans and mice. Its deficiency indicates a poor pregnancy outcome due to defective decidualization, making UCHL1 a potential target for the diagnosis and treatment of miscarriage.

Trophoblast-derived miR-410-5p induces M2 macrophage polarization and mediates immunotolerance at the fetal-maternal interface by targeting the STAT1 signaling pathway.

BACKGROUND: Macrophages phenotypic deviation and immune imbalance play vital roles in pregnancy-associated diseases such as spontaneous miscarriage. Trophoblasts regulate phenotypic changes in macrophages, however, their underlying mechanism during pregnancy remains unclear. Therefore, this study aimed to elucidate the potential function of trophoblast-derived miRNAs (miR-410-5p) in macrophage polarization during pregnancy. METHODS: Patient decidual macrophage tissue samples in spontaneous abortion group and normal pregnancy group (those who had induced abortion for non-medical reasons) were collected at the Reproductive Medicine Center of Renmin Hospital of Wuhan University from April to December 2021. Furthermore, placental villi and decidua tissue samples were collected from patients who had experienced a spontaneous miscarriage and normal pregnant women for validation and subsequent experiments at the Shenzhen Zhongshan Obstetrics & Gynecology Hospital (formerly Shenzhen Zhongshan Urology Hospital), from March 2021 to September 2022. As an animal model, 36 female mice were randomly divided into six groups as follows: naive-control, lipopolysaccharide-model, agomir-negative control prevention, agomir-410-5p prevention, agomir-negative control treatment, and agomir-410-5p treatment groups. We analyzed the miR-410-5p expression in abortion tissue and plasma samples; and supplemented miR-410-5p to evaluate embryonic absorption in vivo. The main source of miR-410-5p at the maternal-fetal interface was analyzed, and the possible target gene, signal transducer and activator of transcription (STAT) 1, of miR-410-5p was predicted. The effect of miR-410-5p and STAT1 regulation on macrophage phenotype, oxidative metabolism, and mitochondrial membrane potential was analyzed in vitro. RESULTS: MiR-410-5p levels were lower in the spontaneous abortion group compared with the normal pregnancy group, and plasma miR-410-5p levels could predict pregnancy and spontaneous abortion. Prophylactic supplementation of miR-410-5p in pregnant mice reduced lipopolysaccharide-mediated embryonic absorption and downregulated the decidual macrophage pro-inflammatory phenotype. MiR-410-5p were mainly distributed in villi, and trophoblasts secreted exosomes-miR-410-5p at the maternal-fetal interface. After macrophages captured exosomes, the cells shifted to the tolerance phenotype. STAT1 was a potential target gene of miR-410-5p. MiR-410-5p bound to STAT1 mRNA, and inhibited the expression of STAT1 protein. STAT1 can drive macrophages to mature to a pro-inflammatory phenotype. MiR-410-5p competitive silencing of STAT1 can avoid macrophage immune disorders. CONCLUSION: MiR-410-5p promotes M2 macrophage polarization by inhibiting STAT1, thus ensuring a healthy pregnancy. These findings are of great significance for diagnosing and preventing spontaneous miscarriage, providing a new perspective for further research in this field.

Assisted reproductive technology treatment failure and the detection of intrauterine HPV through spent embryo transfer media sample.

Cervical human papillomavirus (HPV) infection is believed to increase the risks of pregnancy failure and abortion, however, whether the uterine cavity HPV infection reduces pregnancy rate or increases miscarriage rate remains unclarified in infertile women undergoing assisted reproductive technology (ART) treatment. Therefore, we aimed to assess ART outcomes in the presence of intrauterine HPV. This was a hospital-based multicenter (five reproductive medicine centers) matched cohort study. This study involved 4153 infertile women undergoing in vitro fertilization (IVF) or intracytoplasmic sperm injection treatment in five reproductive medicine centers between October 2018 and 2020. The spent embryo transfer media sample with endometrium tissue were collected and performed with flow-through hybridization and gene chips to detect HPV DNA. According to basic characteristics, HPV-positive and negative patients were matched in a ratio of 1:4 by age, body mass index transfer timing, transfer type, and number of embryos transferred. The primary outcome was pregnancy and clinical miscarriage rates in the transfer cycle underwent HPV detection. 92 HPV-positive and 368 HPV-negative patients were screened and analyzed statistically. Univariate analysis showed uterine cavity HPV infection resulted in lower rates of ongoing pregnancy (31.5% vs. 44.6%; p = 0.023), implantation (32.3% vs. 43.1%; p = 0.026), biochemical pregnancy (47.8% vs. 62.5%; p = 0.010), and clinical pregnancy (40.2% vs. 54.3%; p = 0.015) compared with HPV negative group. The infertile female with positive HPV also had a slightly higher frequency of biochemical miscarriage (15.9% vs. 13.0%; p = 0.610) and clinical miscarriage (24.3% vs. 15.5%; p = 0.188). These findings suggest that HPV infection in the uterine cavity is a high risk for ART failure. HPV screening is recommended before ART treatment, which may be benefit to improving pregnancy outcome.

The endometrial microbiota and early pregnancy loss.

The human endometrium is a dynamic entity that plays a pivotal role in mediating the complex interplay between the mother and developing embryo. Endometrial disruption can lead to pregnancy loss, impacting both maternal physical and psychological health. Recent research suggests that the endometrial microbiota may play a role in this, although the exact mechanisms are still being explored, aided by recent technological advancements and our growing understanding of host immune responses. Suboptimal or dysbiotic vaginal microbiota, characterized by increased microbial diversity and reduced Lactobacillus dominance, has been associated with various adverse reproductive events, including miscarriage. However, the mechanisms linking the lower reproductive tract microbiota with pregnancy loss remain unclear. Recent observational studies implicate a potential microbial continuum between the vaginal and endometrial niche in patients with pregnancy loss; however, transcervical sampling of the low biomass endometrium is highly prone to cross-contamination, which is often not controlled for. In this review, we explore emerging evidence supporting the theory that a dysbiotic endometrial microbiota may modulate key inflammatory pathways required for successful embryo implantation and pregnancy development. We also highlight that a greater understanding of the endometrial microbiota, its relationship with the local endometrial microenvironment, and potential interventions remain a focus for future research.

Natural proliferative phase frozen embryo transfer-a new approach which may facilitate scheduling without hindering pregnancy outcomes.

STUDY QUESTION: How does a natural proliferative phase (NPP) strategy for frozen embryo transfer (FET) compare with the conventional artificial (AC) and natural (NC) endometrial preparation protocols in terms of live birth rates (LBR)? SUMMARY ANSWER: This study supports the hypothesis that, just as for NC, NPP-FET may be a superior alternative to AC in terms of LBR. WHAT IS KNOWN ALREADY: Although FETs are increasing worldwide, the optimal FET protocol is still largely controversial. Despite recent evidence supporting a possibly higher efficacy and safety of NC FETs, their widespread use is limited by the difficulties encountered during cycle monitoring and scheduling. STUDY DESIGN, SIZE, DURATION: In this single center retrospective cohort study, we describe the NPP-FET protocol, in which vaginal progesterone is initiated during the proliferative phase as soon as an endometrium with a thickness of at least 7 mm is identified and ovulation is ruled out, regardless of mean diameter of the dominant follicle. PARTICIPANTS/MATERIALS, SETTING, METHODS: For comparison, we considered all blastocyst stage FET cycles preformed at a private infertility center between January 2010 and June 2022, subdivided according to the following subgroups of endometrial preparation: AC, NPP, and NC. We performed multivariable generalized estimating equations regression analysis to account for the following potential confounding variables: oocyte age at retrieval, oocyte source (autologous without preimplantation genetic testing for aneuploidies (PGT-A) versus autologous with PGT-A versus donated), number of oocytes retrieved/donated, embryo developmental stage (Day 5 versus Day 6), number of embryos transferred, quality of the best embryo transferred, and year of treatment. The main outcome measure was LBR. The secondary outcomes included hCG positive, clinical pregnancy and miscarriage rates, and the following perinatal outcomes: first trimester bleeding, second/third trimester bleeding, preterm rupture of membranes, gestational diabetes, gestational hypertensive disorders (GHD), and gestational age at delivery. MAIN RESULTS AND THE ROLE OF CHANCE: A total of 5791 FET cycles were included in this analysis (2226 AC, 349 NPP, and 3216 NC). The LBR for FET was lower in the AC subgroup when compared to the NPP and NC (38.4%, 49.1%, and 45.2%, respectively; P < 0.01 AC versus NPP and AC versus NC). The rates of miscarriage were also lower in the NPP and NC subgroups when compared to AC (19.7%, 25.0%, and 34.9%, respectively; P < 0.01 NPP versus AC and NC versus AC). Considering perinatal outcomes, NPP-FET and NC were associated with a significantly lower first trimester bleeding compared to AC (17.3%, 14.7%, and 37.6%, respectively; P < 0.01 NPP versus AC and NC versus AC). Additionally, NC was associated with a lower rate of GHD when compared with AC (8.6% versus 14.5%, P < 0.01), while the rate following NPP-FET was 9.4%. LIMITATIONS, REASONS FOR CAUTION: This study is limited by its retrospective design. Moreover, there was also a low number of patients in the NPP subgroup, which may have led the study to be underpowered to detect clinically relevant differences between the subgroups. WIDER IMPLICATIONS OF THE FINDINGS: Our study posits that the NPP-FET protocol may be an effective and safe alternative to both NC and AC, while still allowing for enhanced practicality in patient follow-up and FET scheduling. Further investigation on NPP-FET is warranted, with prospective studies including a larger and more homogeneous subsets of patients. STUDY FUNDING/COMPETING INTEREST(S): This research was supported by the IVI-RMA-Lisbon (2008-LIS-053-CG). The authors did not receive any funding for this study. The authors have no competing interests. TRIAL REGISTRATION NUMBER: Not applicable.

Predicting Infertility: How Genetic Variants in Oocyte Spindle Genes Affect Egg Quality.

Successful reproduction relies on the union of a single chromosomally normal egg and sperm. Chromosomally normal eggs develop from precursor cells, called oocytes, that have undergone accurate chromosome segregation. The process of chromosome segregation is governed by the oocyte spindle, a unique cytoskeletal machine that splits chromatin content of the meiotically dividing oocyte. The oocyte spindle develops and functions in an idiosyncratic process, which is vulnerable to genetic variation in spindle-associated proteins. Human genetic variants in several spindle-associated proteins are associated with poor clinical fertility outcomes, suggesting that heritable etiologies for oocyte dysfunction leading to infertility exist and that the spindle is a crux for female fertility. This chapter examines the mammalian oocyte spindle through the lens of human genetic variation, covering the genes TUBB8, TACC3, CEP120, AURKA, AURKC, AURKB, BUB1B, and CDC20. Specifically, it explores how patient-identified variants perturb spindle development and function, and it links these molecular changes in the oocyte to their cognate clinical consequences, such as oocyte maturation arrest, elevated egg aneuploidy, primary ovarian insufficiency, and recurrent pregnancy loss. This discussion demonstrates that small genetic errors in oocyte meiosis can result in remarkably far-ranging embryonic consequences, and thus reveals the importance of the oocyte's fine machinery in sustaining life.

The relationship between thyroid autoantibodies and X chromosome monosomy in the chorionic tissue of patients with missed miscarriage.

OBJECTIVE: The aim of this study was to investigate the relationship between thyroid autoantibodies (TGAb and TPOAb) and X chromosome monosomy in the chorionic tissue of patients with missed early miscarriage. METHODS: The baseline data, thyroid function, thyroid antibody and the chromosomes from the chorionic tissue of 228 patients with missed early miscarriage were examined. RESULTS: (1) Among the 228 patients, 121 had a normal chromosome number, and 107 had an abnormal chromosome number. The majority of them were autosomal trisomy, of which trisomy 16 (40.19%) was predominant. Sex chromosome monosomy (28.04%) was secondary. (2) Among the 228 patients, 208 patients in this study had normal thyroid function (including 134 cases of negative thyroid antibodies and 74 cases of positive thyroid antibodies alone); 6 patients had abnormal thyroid function (including 2 cases of clinical hyperthyroidism, 3 cases of subclinical hypothyroidism, 1 case of hypothyroxinemia); and 14 patients had normal TSH and elevated T4 alone.(3) After exclusion of patients with thyroid function abnormalities, there were no significant differences in baseline data between the normal chromosome group and the abnormal chromosome group (P > 0.05). However, there was a significant difference in TGAb and TPOAb between the normal chromosome and abnormal chromosome group with 45, X karyotype, with a higher proportion of TGAb and/or TPOAb positivity in the 45, X karyotype group (P < 0.05). Additionally, compared to TGAb and/or TPOAb-positive patients, the risk of X chromosome monosomy was significantly reduced in TGAb and TPOAb-negative patients (P < 0.05). Moreover, both TGAb and TPOAb titer values in the X chromosome monosomy group were higher than those in the chromosomally normal group (P < 0.05). CONCLUSION: There is a correlation between TGAb, TPOAb and X chromosome monosomy in the chorionic tissue of patients with missed early miscarriage, although the mechanism remains to be further investigated.

Association of serum vitamin D concentration and miscarriage rate in women with first-trimester threatened miscarriage.

RESEARCH QUESTION: Is low serum 25-hydroxyvitamin D (25(OH)D) associated with an increased risk of miscarriage in women who presented with threatened miscarriage to the Early Pregnancy Assessment Clinic (EPAC)? DESIGN: This was a secondary retrospective analysis using archived serum samples from a randomized, double-blind, placebo-controlled trial. Stored serum samples from 371 women presenting to the EPAC with threatened miscarriage during the first trimester were assayed for 25(OH)D by liquid chromatography-mass spectrometry. RESULTS: The overall miscarriage rate was 45/371 (12.1%) in the whole cohort. After grouping vitamin D insufficiency and vitamin D sufficiency together into a 'non-deficient' group and excluding participants who underwent termination of pregnancy, there was no difference in the miscarriage rate between those who were vitamin D deficient compared with those who were not (25/205, 12.2% versus 20/157, 12.7%, P= 0.877, odds ratio 0.951, 95% CI 0.507-1.784). When analysed according to the number of gestational weeks, the miscarriage rate was significantly higher in the vitamin D non-deficient group than the vitamin D-deficient group in women who presented at 6 gestational weeks or earlier (13/33 [39.4%] versus 10/58 [17.2%], P= 0.019), but there were no statistically significant differences between the two groups presenting at later gestations. There was no difference in the vitamin D level in women who had a miscarriage compared with those who had a live birth (48 [37-57] versus 47 [37-58] nmol/l, P= 0.725 median [25th-75th percentile]). CONCLUSIONS: A low serum vitamin D concentration was not associated with an increased risk of miscarriage in women with threatened miscarriage presenting to the EPAC.

Use of artificial intelligence embryo selection based on static images to predict first-trimester pregnancy loss.

RESEARCH QUESTION: Can an artificial intelligence embryo selection assistant predict the incidence of first-trimester spontaneous abortion using static images of IVF embryos? DESIGN: In a blind, retrospective study, a cohort of 172 blastocysts from IVF cases with single embryo transfer and a positive biochemical pregnancy test was ranked retrospectively by the artificial intelligence morphometric algorithm ERICA. Making use of static embryo images from a light microscope, each blastocyst was assigned to one of four possible groups (optimal, good, fair or poor), and linear regression was used to correlate the results with the presence or absence of a normal fetal heart beat as an indicator of ongoing pregnancy or spontaneous abortion, respectively. Additional analyses included modelling for recipient age and chromosomal status established by preimplantation genetic testing for aneuploidy (PGT-A). RESULTS: Embryos classified as optimal/good had a lower incidence of spontaneous abortion (16.1%) compared with embryos classified as fair/poor (25%; OR = 0.46, P = 0.005). The incidence of spontaneous abortion in chromosomally normal embryos (determined by PGT-A) was 13.3% for optimal/good embryos and 20.0% for fair/poor embryos, although the difference was not significant (P = 0.531). There was a significant association between embryo rank and recipient age (P = 0.018), in that the incidence of spontaneous abortion was unexpectedly lower in older recipients (21.3% for age ≤35 years, 17.9% for age 36-38 years, 16.4% for age ≥39 years; OR = 0.354, P = 0.0181). Overall, these results support correlation between risk of spontaneous abortion and embryo rank as determined by artificial intelligence; classification accuracy was calculated to be 67.4%. CONCLUSIONS: This preliminary study suggests that artificial intelligence (ERICA), which was designed as a ranking system to assist with embryo transfer decisions and ploidy prediction, may also be useful to provide information for couples on the risk of spontaneous abortion. Future work will include a larger sample size and karyotyping of miscarried pregnancy tissue.