Infertility is becoming increasingly common and more people are turning to assisted reproductive technologies. However, success rates remain disappointingly low, and improving outcomes for every treatment is a major priority. Accurate embryo placement during embryo transfer (ET) is critical for implantation and livebirth. While two-dimensional (2D) ultrasound-guided embryo transfer (USGET) approaches are standard, evidence for four-dimensional (4D)USGET is limited. This review aimed to determine whether 4DUSGET improves embryo placement accuracy and clinical reproductive outcomes, informing clinical practice and guiding future research. A narrative review of literature across databases was performed. Data extraction included study design, sample size, embryo placement technique, and pregnancy outcomes. 4DUSGET was associated with enhanced accuracy of embryo deposition, particularly in women with abnormal uterine anatomy or when targeting the maximal implantation potential point. Several studies reported higher clinical pregnancy and livebirth with 4D compared to 2D guidance. Evidence base is limited by a small number of studies, heterogeneous outcomes and potential bias inherent to narrative syntheses, making definitive conclusions challenging. Nonetheless, emerging data suggest 4DUSGET may provide meaningful benefit in anatomically complex cases with the potential to improve IVF success rates. Trials are needed to confirm findings and establish generalisability across IVF populations.

Background Miscarriage and ectopic pregnancy are among the most common early pregnancy complications, yet contemporary national trends and associated inequalities in England remain poorly characterised. This study examined 20-year temporal patterns in hospital admissions for miscarriage and ectopic pregnancy, with additional stratification by socioeconomic deprivation and age. Methods National admissions data from 2004 to 2024, curated by NHS England, were extracted from Hospital Episode Statistics and the Maternity Services Data Set. Annual counts of miscarriage (ICD-10 O02–O03) and ectopic pregnancy (ICD-10 O00), deliveries, deprivation deciles, and age groups were analysed. Joinpoint regression (version 5.0) was used to identify significant changes in trends, calculating Annual Percent Change (APC) and Average Annual Percent Change (AAPC). Findings Miscarriage admissions declined significantly between 2018 and 2021 (APC = −4.44∗%; 95% CI: −7.4218 to −0.7135; p = 0.03), followed by a modest rise after 2021 (APC = +2.823%; 95% CI: −1.8311 to 8.8970; p = 0.13). Ectopic pregnancy admissions increased significantly up to 2012 (APC +2.82%; 95% CI: 1.3845–3.8309; p = 0.007), declined with the introduction of conservative management guidelines (APC = −2.97%; 95% CI: −3.9393 to 3.827; p = 0.15) and rose again after 2021 (APC = +4.23∗% (95% CI: 2.1194–7.1943; p < 0.001). A persistent deprivation gradient was observed, with the most deprived deciles consistently experiencing the highest admissions (around two-fold difference). The proportion of admissions among women aged 25–34 years increased (approximately 40–50%) for both outcomes. Interpretation Persistent socioeconomic inequalities reflect a combination of population structure, higher prevalence of modifiable risk factors and inequitable access to care. Strengthening equitable access, tailored outreach through digital platforms and preventive strategies addressing modifiable risk factors may help optimise early pregnancy care and reduce avoidable emergency admissions. Findings should be interpreted with caution due to limited risk factor, parity, and age–deprivation data. Funding None.

Primary dysmenorrhea affects an estimated 73% of people who menstruate worldwide. This high global prevalence underscores the need for effective strategies to address the substantial burden of menstrual pain. Despite this, current treatment options remain limited. Cannabidiol (CBD) treatments have been proposed for managing primary dysmenorrhea; however, their safety and efficacy remain largely unstudied. This two-part study presents a comprehensive evaluation of the safety and efficacy of CBD-coated tampons. The first part focuses on preclinical assessments, including irritation, toxic shock syndrome risk, acute systemic toxicity, skin sensitisation, vaginal irritation, and material-mediated pyrogenicity. The second part combines post-market surveillance data, including clinical complications collected from 2019-2024, and survey data collected from 2022-2024, including Manonski pain scores for rating menstrual pain severity prior to and during CBD tampon use. In preclinical assessments, all safety benchmarks were met. A total of 148 clinical complications were reported in relation to CBD-coated tampon use, equating to a prevalence of 0.58% (148/25327, 95% Confidence interval [CI]:0.49 - 0.68%), below the predefined target of <1%. From 42,000 users who were sent the survey, we received 2,123 responses from CBD‑coated tampon users. Before CBD tampon use, the average self-reported Mankoski Pain Score was 6.35 (95% CI: 6.27–6.43, SD = 1.83). During use, mean scores were 3.78 (95% CI: 3.69–3.87, SD = 2.13), representing a mean reduction of 2.57 (95% CI: 2.45–2.69). These findings, corroborated by results from a previously published randomized controlled trial, provide complementary evidence that CBD-coated tampons may offer a safe and effective option for menstrual pain management. Future, large randomised control trials should explore optimum patterns of use of CBD-coated tampons.

Introduction: Chronic pelvic pain (CPP) represents a significant health issue among women, profoundly impacting their quality of life. Current treatment modalities primarily include hormonal therapy, analgesics, or surgical interventions, which may have side effects or be unsuitable for women attempting to conceive. The objective of this study is to determine if cannabidiol (CBD) is an acceptable non-hormonal self-management option for women with CPP. Methods: A prospective, cross sectional observational questionnaire study that included 200 women with CPP who attended the gynaecological department at the Liverpool Women's Hospital (LWH), UK, over a six-month period. The main outcomes included acceptability of CBD as a non-hormonal treatment option for CPP, current treatments/self-management strategies utilised, and interest in participation in future trials investigating CBD for CPP management. Results: Sixteen % (n = 32) of the questioned cohort were taking alternative treatments, 16.3 % (n = 26) had tried cannabis (prescribed/illicit), and 21.3 % (n = 34) had tried Hemp/CBD oil as an alternative treatment option. A total of 82.5 % (n =165) of respondents were willing to try CBD; 73.9 % (n =139) oral, 69.7 % (n =131) a skin patch, 72.3 % (n = 136) a balm/gel and 33 % (n = 62) a CBD infused tampon. Most women, 75.5 % (n = 151), revealed their willingness to take part in future trials involving CBD as a treatment option. Conclusion: CPP remains inadequately treated, leading many women to seek alternative therapies. CBD is considered an acceptable option, with a high proportion of surveyed women reporting current or past use to manage their symptoms.

Background: Abortion is a core component of reproductive healthcare and a critical determinant of maternal health outcomes. Globally, approximately 73 million abortions occur annually, with unsafe abortion contributing to 4.7–13.2% of maternal deaths, primarily in low- and middle-income countries (LMICs). Legal frameworks governing abortion vary widely, ranging from total prohibition to fully integrated care systems. Access is further shaped by health system capacity, procedural barriers, and socio-economic inequities. In an increasingly globalised world, migration adds complexity, as individuals move between countries with differing policies, influencing both direct access to care and regional healthcare dynamics. Understanding these intersecting factors is essential for improving reproductive health equity and reducing preventable morbidity and mortality. Methods: A global comparative analysis was conducted using two integrated datasets covering 100 countries. The first dataset captured legal, operational, and contextual variables, including gestational limits, funding mechanisms, provider cadres, and telemedicine availability. The second dataset provided demographic, socio-economic, and health system indicators. Access Scores were derived from weighted indicators on a 0–10 scale. Analyses included descriptive statistics, bivariate associations, and multivariable ordinal logistic regression. An intersectional approach explored disparities across income groups, geographic regions, and migration pathways, with visualisation tools such as heatmaps, bubble plots, and diaspora exposure differentials. Results: Countries with telemedicine-enabled early medical abortion (tele-EMA) were significantly associated with higher Access Scores (OR ≈1.45), while each additional mandated waiting day reduced odds of liberal access by 7%. Mid-level provider authorisation and public funding alone did not predict improved access. Migration analysis revealed that LMIC-to-HIC flows resulted in marked improvements in abortion access, though benefits were unevenly distributed, leaving vulnerable populations behind. African and Asian LMICs had the lowest Access Scores, reflecting systemic underfunding and restrictive laws. Conclusion: Abortion access is shaped by functional health system design rather than geography alone. Removing procedural barriers, expanding telemedicine, and embedding services within integrated health systems are essential to achieving equitable, sustainable reproductive healthcare worldwide.

Stage-specific embryonic antigen-1 (SSEA-1)+ endometrial epithelial cells (EECs) assume the postulated stem/progenitor cell niche within the human endometrium. Previous studies have demonstrated that isolated SSEA-1+ cells have a higher capacity to generate organoids in a three-dimensional matrix, a lower steroid hormone receptor expression, and higher telomerase activity with longer telomere lengths. Here, we present the transcriptomic profile of isolated SSEA-1+ EECs from eight endometrial biopsies compared to SSEA-1- EECs. Transcriptome and pathway analysis indicate that SSEA-1+ EECs play an important role in endometrial regeneration, remodeling and neovascularization as expected from a basal progenitor population. We show that SSEA-1+ EECs play a role in endometrial tissue homeostasis and tumor suppression, and bioinformatically identify potential upstream regulators such as SPDEF and TGFB1, which may be involved in these mechanisms. In vitro EEC organoid models also demonstrate SSEA-1+ EECs to exhibit estrogen responsive proliferation evidenced by stronger immunostaining for progesterone receptor and Ki-67. Our data further suggest a more quiescent, less hormone responsive phenotype for SSEA-1+ EECs that co-localize to SOX9+ EECs within in silico analysis, thus validating previous studies.

Background Human intervention to terminate a pregnancy, while medically effected through a range of pharmaceutical, surgical, and other approaches, is generally referred to in English as “abortion.” It is a fundamental aspect of reproductive healthcare and its availability, regulation, and limits (cultural, familial, legal) are well-documented determinants of women’s and girls’ health worldwide. Despite its routine nature in many health systems, it remains a deeply sensitive issue shaped by cultural, legal, religious, and political factors. Globally, an estimated 73 million abortions occur annually, yet access to safe and timely care is highly variable. In settings where abortion is legal and integrated into healthcare services, it is one of the safest medical procedures. Conversely, restrictive policies force individuals to seek unsafe alternatives, contributing to preventable maternal deaths and long-term health complications. Laws and regulations play a pivotal role in shaping access, but these are influenced by societal norms and often create inequities within and between countries. Methods A systematic review was conducted to identify, collate, and analyse publicly available abortion policies and legislation in English from 1980 to 2025. Data sources included peer-reviewed literature, legal databases, national government portals, and grey literature from global health organisations. Policies were screened, extracted, and appraised using a structured framework. A thematic and contextual analysis was undertaken to explore the legal, operational, and governance components of abortion policies and their implications for access and equity. ResultsPolicies from over 100 countries were included, demonstrating significant global variation. Liberal frameworks, such as those in Iceland, Sweden, England, and New Zealand, were associated with early, safe access through broad on-demand gestational limits and integrated care. Restrictive or grounds-based models, common in parts of Eastern Europe, the Middle East, and Latin America, relied on multi-clinician approvals, waiting periods, and documentation, creating delays and inequities. Federated systems, including the United States and Australia, showed marked regional disparities. Criminal penalties in several countries had a chilling effect, driving cross-border travel and unsafe abortion. Conclusion Global abortion policies vary widely, with many failing to translate legal rights into equitable, practical access. Evidence-informed reforms that integrate health systems research and cultural context are urgently needed to reduce preventable harm and promote reproductive justice.

Recurrent implantation failure (RIF) is a devastating condition that leaves many undergoing fertility treatment childless. The human endometrium is receptive to a blastocyst for a brief period, the window of implantation. Critical knowledge underpinning biological processes leading to RIF, essential for effective treatment, is lacking. We employed spatial transcriptomics to define region- and cell-type-specific differences in endometrial gene expression in luteinizing hormone timed biopsies between women with RIF (n = 8) and fertile controls (FC) (n = 8). Differentially expressed genes (DEGs) were identified when comparing endometrial regions between FC and RIF (685 luminal epithelium, 293 glandular epithelium, 419 subluminal stroma, 264 functionalis stroma, 1,125 subluminal stromal CD45+ leukocytes, and 1,049 functionalis stromal CD56+ leukocytes). Only 57 DEGs were common to all subregions and cell types, which highlights that multiple DEGs are lost when the endometrium is examined as a single entity. When RIF-specific DEGs were leveraged against knowledge from mouse genetic models, genes associated with aberrant embryo implantation phenotypes were observed, mostly in immune cell populations. Dysregulated pathways in specific endometrial regions included the "WNT signaling pathway," altered in the functionalis and subluminal stroma. "Response to estradiol" and "ovulation cycle" pathways were dysregulated in the subluminal stroma. In silico drug screening identified potential compounds that can reverse the RIF gene expression profile (e.g., raloxifene, bisoprolol). Our findings, in a well-characterized cohort, highly endorse consideration of each endometrial region and cell type as separate entities. Ignoring individual regions and composite cell populations will overlook important aberrations, forego potential treatment targets, and lead to research waste pursuing clinically irrelevant treatment options.

Introduction: Surrogacy is a rapidly evolving area of reproductive health that spans ethical, legal, clinical, and societal dimensions. Policies governing surrogacy vary widely across countries, shaping access to services, safeguarding measures, and the protection of women and children. While some nations permit regulated altruistic or commercial surrogacy, others impose outright bans, creating global disparities and driving reproductive travel. This review examined publicly available surrogacy policies and guidance, with a focus on commissioning decisions, operational processes, and international cross-border complexities. Methods: Following PRISMA guidelines, a systematic search publicly accessible English-language surrogacy policies and guidance documents were identified through a comprehensive search of health service commissioning bodies, government agencies, and professional organisations. Thematic analysis was conducted to explore policy scope, legal frameworks, safeguarding procedures, and international variation. Policies were then compared to assess areas of convergence and divergence across global settings. Results: Globally, surrogacy regulation is highly fragmented. In Europe, most countries prohibit commercial surrogacy and, in some cases, altruistic arrangements, while nations such as the UK, Ireland, and Greece allow tightly controlled altruistic surrogacy. North America shows a patchwork approach, with some US states and Canada permitting altruistic or compensated arrangements under varying levels of regulation. In Asia, historical hubs such as India and Thailand have shifted from permissive commercial surrogacy to restrictive altruistic-only models following concerns over exploitation. Africa remains largely unregulated, except for South Africa’s comprehensive legal framework. Across settings, recurrent themes included safeguarding concerns, ethical debates over exploitation versus autonomy, and challenges in determining legal parentage and nationality. Cross-border arrangements amplify these complexities, often leaving children stateless or without clear legal protections. Conclusion: The absence of harmonised frameworks perpetuates inequities in women’s health and cross-border surrogacy, often exposing individuals to financial, legal, and health risks. These challenges underscore the urgent need for evidence-based policies and fairer, more equitable approaches to surrogacy.

Is the urine metabolome predictive of early pregnancy outcomes? The urine metabolome is moderately predictive of live normally-sited pregnancies when compared to a pregnancy with an adverse outcome. Approximately 20% of all pregnancies are lost in the first trimester and a further 2% are ectopic (EP). Symptoms of pregnancy loss and EP (bleeding +/- pelvic pain) are extremely common, but often indistinguishable from live normally sited pregnancies (LNSP). Pregnancies that will not progress (non-viable or EP), defined together as combined adverse outcomes (CAO), can be devastating for the sufferer, necessitating multiple hospital attendances and invasive tests. Therefore, it is of paramount importance that new non-invasive tests are developed to improve diagnostic accuracy in early pregnancy. Here, we investigate the urine metabolome to identify novel biomarkers of pregnancy outcome. This was a prospective cohort study (EXPEDITE). 354 pregnant women <10 weeks’ gestation with pain and/or bleeding were recruited over a period of 36 months at Liverpool Women’s Hospital, a tertiary referral centre. Pregnancy outcomes were categorised according to ESHRE guidelines as LNSP (n=160), miscarriage (n=93), tubal EP (tEP, n=54) or pregnancy of unknown location (PUL, n=47). Urine was analysed by liquid chromatography coupled quadrupole time of flight mass spectrometry and nuclear magnetic resonance spectroscopy. Relative metabolite abundances underwent univariate and multivariate statistical analysis using MetaboAnalyst 6.0 and custom-built R scripts (p-value false discovery rate adjusted). Discriminant analyses were cross-validated using area under receiver operating characteristic curves (AUROC). Demographic variables including age, BMI and ethnicity were comparable across groups. Univariate statistical analysis identified six metabolite abundances that differed significantly between the four pregnancy outcomes. Taurine abundance was significantly higher in the LNSP group compared to miscarriage, PUL and tEP. Multivariate partial least squares discriminant analysis (PLS-DA) models of all groups failed to accurately predict pregnancy outcomes. When miscarriage, PUL and tEP were combined into a CAO group and compared to LNSP, eight metabolite abundances (adenosine, arginine, deoxyguanosine, histidine, hydroxylysine, hypoxanthine, L-2-aminoadipic acid, and taurine) were significantly different. The identity of metabolites with significantly different abundances were confirmed by NMR spectroscopy. Taurine demonstrated modest predictive accuracy (AUC=0.70, CI = 0.64-0.75) for differentiating LNSP from CAO. Taurine is known to accumulate at higher levels in maternal tissue during pregnancy. In summary, this study has identified a urine metabolite profile and potential biomarkers associated with live normally-sited pregnancy in the first trimester. The number of tEPs and PULs were relatively low compared to other outcomes. This study followed a semi-targeted approach to metabolite annotation. An untargeted approach may identify additional metabolite biomarkers for diagnosing early pregnancy outcome. The urine metabolome could offer novel pregnancy outcome biomarkers. Taurine levels are known to increase during pregnancy, but its utility as a biomarker has not been explored previously. A diagnostic test to confirm LNSP and thus rule out life-threatening outcomes could significantly reduce patient anxiety and avoid unnecessary repeat procedures. No

Purpose:It is increasingly acknowledged that public acceptability should be considered when designing, evaluating, and implementing healthcare interventions; especially for vulnerable groups. Patients and Methods:A voluntary, self-reported, anonymous questionnaire with ethical approval and patient and public involvement was distributed online through social media over a 6-month period to explore acceptability of diagnostic tests. Results:Ninety-three individuals replied to the questionnaire, of which the majority were female (89.2%) heterosexual (92.4%) white (81.6%) and resided in England (94.6%). The most encountered diagnostic test was an X-ray (92.4%) and the least encountered test was a bone marrow biopsy with local anaesthetic (0%). A sputum sample test was the most perfectly acceptable investigation (83.8%). One percent of participants felt that the cervical smear test was perfectly acceptable With reference to hysteroscopy, 44% felt a hysteroscopy was perfectly acceptable under general anaesthesia, compared to no participants with local anaesthetic or sedation. Forty one percent of participants felt a diagnostic laparoscopy was perfectly acceptable. Conclusion:The findings from this study provide insight into the acceptability of medical tests from a patient perspective and will inform a more explorative qualitative study to ensure researchers are aiming to produce tests that are sensitive, specific and importantly acceptable.

Rates of infertility are rising, and informed decision making is an essential part of reproductive life planning with the knowledge that ART success decreases dramatically while a woman’s age increases and that high costs can often be incurred during fertility treatment. We aimed to determine the current knowledge of infertility and its treatments in the general public through an online survey. We received 360 complete responses. The average age of respondents was 35 years with most respondents being female (90%), heterosexual (88%), white (85%) and university educated (79%). Of the total, 49% had children and 23% had a condition that affects their fertility; 41% had concerns about future fertility and 78% knew someone who had had fertility treatment. Participants’ understanding of basic reproductive biology and causes of infertility varied with correct responses to questions ranging from 44% to 93%. Understanding of IVF outcomes was poorer with only 32% to 55% of responses being correct, and 76% of respondents felt that their education in fertility was inadequate. This survey highlights the inconsistencies in the general public’s understanding of infertility in this relatively educated population. With increasing demands on fertility services and limited public funds, better education is essential to ensure patients are fully informed with regard to their reproductive life planning.

BackgroundAn increased body mass index (BMI) can lead to subfertility; however, current literature fails to exclude the effect of other confounding medical conditions, raising questions regarding the direct link between increased BMI and fertility outcomes.ObjectivesTo conduct a systematic review and meta-analysis to elucidate the effects of increased BMI on fertility outcomes in females with no other comorbidities.Search strategyA comprehensive search was conducted using EMBASE, MEDLINE and the Cochrane library from January 2000 until July 2023.Data collection and analysisTwo authors independently conducted data extraction and assessed study quality. Odds ratio (OR) (dichotomous data), standardised mean difference (SMD) (continuous data) and 95% CIs were calculated.Main resultsNine eligible studies were identified: one natural conception and eight assisted reproductive technology (ART). Aggregated data revealed women with BMI ≥25 were less likely to attain clinical pregnancy (OR 0.76, 95% CIs 0.62 to 0.93, p=0.007), with BMI ≥30 associated with a further decreased likelihood of clinical pregnancy (OR 0.61, 95% CIs 0.39 to 0.98, p=0.04). Women with raised BMI required longer duration of stimulation (SMD=0.08, 95% CIs 0.00 to 0.16, p=0.04) and obtained reduced oocytes (SMD=−0.11, 95% CIs −0.18 to −0.04, p=0.002).ConclusionsThese data demonstrate an adverse impact of being overweight/obese on ART outcomes in women with no other diagnosed medical comorbidities and highlight the distinct lack of data concerning the effects of isolated obesity on natural conception. Infertility represents an enormous burden for couples and society; it is essential to identify and tackle modifiable risk factors to improve chances of conception.PROSPERO registration numberCRD42022293631.

Abstract Study question Will the transcriptional profile of SSEA-1+ endometrial epithelial cells (EECs) explain their functional role, which can be explored in an in vitro endometrial organoid model? Summary answer SSEA-1+ EECs demonstrate differentially expressed genes (DEGs) and associated functional pathways expected from a basal stem/progenitor cell (SPC) population, agreeing with the in vitro experiments. What is known already Endometrial SPCs are postulated to reside in the basalis and to be responsible for the full phenotypic and functional restoration of the endometrial functionalis layer. SSEA-1+ EECs assume the postulated basalis SPC niche. Previous studies demonstrated isolated SSEA-1+ EECs to have a higher capacity to generate organoids in 3D matrix and display growth like that observed after endometrial denudation. They have lower steroid hormone expression and higher telomerase activity with longer telomere lengths, all suggesting a SPC phenotype. SSEA-1+ EECs co-express nuclear SRY-box transcription factor 9 (nSOX9) and nuclear b-catenin, suggesting an activated Wnt pathway. Study design, size, duration Endometrial samples were collected from eight pre-menopausal women attending the Liverpool Women’s Hospital for benign gynaecological procedures, aged 30-47 years. These patients were having regular menstrual cycles and had not been on any hormonal therapy for at least three months prior to enrolment. Three further endometrial samples were obtained for 3D EEC organoid culture studies. Participants/materials, setting, methods Magnetic-activated cell sorting was used to isolate SSEA-1 enriched/depleted EECs from freshly harvested endometrial samples. Microarray analysis was performed using Agilent human arrays. DEGs and pathway enrichment analysis were explored using R-studio and Ingenuity Pathway Analysis (IPA). Internal and external validation used RT-qPCR, dual-immunofluorescence, and comparison against publicly available endometrial single cell spatial transcriptomic data. Human EEC organoids models were employed to assess hormonal regulation of SSEA-1 expression using immunohistochemistry. Main results and the role of chance SSEA-1+ EECs have a distinct transcriptional profile, with 1,059 DEGs compared with SSEA-1- EECs. Pathway analysis highlighted their role in endometrial regeneration, adhesion, remodelling, and neovascularisation, enriching for pathways such as ‘extracellular matrix structural constituent’, ‘epithelial to mesenchymal transition’, ‘angiogenesis’, ‘TNFα signalling via NFKB’ and ‘Notch signalling’. IPA’s biological functions demonstrated their involvement in tissue homeostasis, tumour suppression and their more quiescent SPC phenotype, with activation of ‘organismal death’ and inhibition of ‘cell movement/migration’ and ‘cell movement/migration of tumour cell lines’. The activation of canonical pathways such as ‘PTEN signalling’ and ‘endocannabinoid cancer inhibition’ demonstrated their fine equilibrium to drive proliferation during regeneration, whilst providing protection from hyperplastic/carcinogenic transformation. Ten selected DEGs were internally validated using RT-qPCR, demonstrating concordance. Dual-immunofluorescence of gene products of DEGs MMP7, MMP26, C11orf52 and CD47 confirmed co-localisation alongside SSEA-1 in an external biological cohort of endometrial samples. External in silico validation using the Garcia-Alonso et al endometrial single-cell transcriptomics dataset, mapped significantly upregulated DEGs MMP7 and MMP26 to mainly SOX9+ and SOX9+/LGR5+ EECs. EEC organoids exposed to hormones (including oestradiol) demonstrated an induction of proliferation and higher proportion of organoids expressing SSEA-1 (46.8% vs 67%) simulating endometrial glandular regeneration process. Limitations, reasons for caution Freshly isolated/sorted EECs were obtained from women at different menstrual cycle phases. Our organoid model system only contained EECs without the stromal component, thus, was not suitable to assess progestogenic response of EECs that occur in vivo. Wider implications of the findings This study provides novel information on human SSEA-1+ EECs, suggesting their pivotal role in endometrial regeneration. Since endometrial epithelial SPCs make a vital contribution to endometrial repair and pregnancy establishment, characterising of these cells in health will allow the development of targeted novel therapies on aberrant SPCs within gynaecological disease. Trial registration number Not applicable

A significant number of pregnancies are lost in the first trimester and 1–2% are ectopic pregnancies (EPs). Early pregnancy loss in general can cause significant morbidity with bleeding or infection, while EPs are the leading cause of maternal mortality in the first trimester. Symptoms of pregnancy loss and EP are very similar (including pain and bleeding); however, these symptoms are also common in live normally sited pregnancies (LNSP). To date, no biomarkers have been identified to differentiate LNSP from pregnancies that will not progress beyond early gestation (non-viable or EPs), defined together as combined adverse outcomes (CAO). In this study, we present a novel machine learning pipeline to create prediction models that identify a composite biomarker to differentiate LNSP from CAO in symptomatic women. This prospective cohort study included 370 participants. A single blood sample was prospectively collected from participants on first emergency presentation prior to final clinical diagnosis of pregnancy outcome: LNSP, miscarriage, pregnancy of unknown location (PUL) or tubal EP (tEP). Miscarriage, PUL and tEP were grouped together into a CAO group. Human chorionic gonadotrophin β (β-hCG) and progesterone concentrations were measured in plasma. Serum samples were subjected to untargeted metabolomic profiling. The cohort was randomly split into train and validation data sets, with the train data set subjected to variable selection. Nine metabolite signals were identified as key discriminators of LNSP versus CAO. Random forest models were constructed using stable metabolite signals alone, or in combination with plasma hormone concentrations and demographic data. When comparing LNSP with CAO, a model with stable metabolite signals only demonstrated a modest predictive accuracy (0.68), which was comparable to a model of β-hCG and progesterone (0.71). The best model for LNSP prediction comprised stable metabolite signals and hormone concentrations (accuracy = 0.79). In conclusion, serum metabolite levels and biochemical markers from a single blood sample possess modest predictive utility in differentiating LNSP from CAO pregnancies upon first presentation, which is improved by variable selection and combination using machine learning. A diagnostic test to confirm LNSP and thus exclude pregnancies affecting maternal morbidity and potentially life-threatening outcomes would be invaluable in emergency situations.

STUDY QUESTION: Does endometrial compaction (EC) help predict pregnancy outcomes in those undergoing ART? SUMMARY ANSWER: EC is associated with a significantly higher clinical pregnancy rate (CPR) and ongoing pregnancy rate (OPR), but this does not translate to live birth rate (LBR). WHAT IS KNOWN ALREADY: EC describes the progesterone-induced decrease in endometrial thickness, which may be observed following the end of the proliferative phase, prior to embryo transfer. EC is proposed as a non-invasive tool to help predict pregnancy outcome in those undergoing ART, however, published data is conflicting. STUDY DESIGN, SIZE, DURATION: A literature search was carried out by two independent authors using PubMed, Cochrane Library, MEDLINE, Embase, Science Direct, Scopus, and Web of Science from inception of databases to May 2023. All peer-reviewed studies reporting EC and pregnancy outcomes in patients undergoing IVF/ICSI treatment were included. PARTICIPANTS/MATERIALS, SETTING, METHODS: The primary outcome is LBR. Secondary outcomes included other pregnancy metrics (positive pregnancy test (PPT), CPR, OPR, miscarriage rate (MR)) and rate of EC. Comparative meta-analyses comparing EC and no EC were conducted for each outcome using a random-effects model if I2 > 50%. The Mantel-Haenszel method was applied for pooling dichotomous data. Results are presented as odds ratios (OR) with 95% CI. MAIN RESULTS AND THE ROLE OF CHANCE: Out of 4030 screened articles, 21 cohort studies were included in the final analysis (n = 27 857). No significant difference was found between LBR in the EC versus the no EC group (OR 0.95; 95% CI 0.87-1.04). OPR was significantly higher within the EC group (OR 1.61; 95% CI 1.09-2.38), particularly when EC >= 15% compared to no EC (OR 3.52; 95% CI 2.36-5.23). CPR was inconsistently defined across the studies, affecting the findings. When defined as a viable intrauterine pregnancy <12 weeks, the EC group had significantly higher CPR than no EC (OR 1.83; 95% CI 1.15-2.92). No significant differences were found between EC and no EC for PPT (OR 1.54; 95% CI 0.97-2.45) or MR (OR 1.06; 95% CI 0.92-1.56). The pooled weighted incidence of EC across all studies was 32% (95% CI 26-38%). LIMITATIONS, REASONS FOR CAUTION: Heterogeneity due to differences between reported pregnancy outcomes, definition of EC, method of ultrasound, and cycle protocol may account for the lack of translation between CPR/OPR and LBR findings; thus, all pooled data should be viewed with an element of caution. WIDER IMPLICATIONS OF THE FINDINGS: In this dataset, the significantly higher CPR/OPR with EC does not translate to LBR. Although stratification of women according to EC cannot currently be recommended in clinical practice, a large and well-designed clinical trial to rigorously assess EC as a non-invasive predictor of a successful pregnancy is warranted. We urge for consistent outcome reporting to be mandated for ART trials so that data can be pooled, compared, and concluded on. STUDY FUNDING/COMPETING INTEREST(S): H.A. was supported by the Hewitt Fertility Centre. S.G.P. and J.W. were supported by the Liverpool University Hospital NHS Foundation Trust. D.K.H. was supported by a Wellbeing of Women project grant (RG2137) and MRC clinical research training fellowship (MR/V007238/1). N.T. was supported by the National Institute for Health and Care Research. D.K.H. had received honoraria for consultancy for Theramex and has received payment for presentations from Theramex and Gideon Richter. The remaining authors have no conflicts of interest to report.