BackgroundRecurrent implantation failure (RIF) remains a significant challenge in reproductive medicine, with diagnostic approaches that are limited and widely debated. This systematic review evaluates whether fluid-based biomarkers from blood, uterine fluid, and menstrual fluid can provide more accessible and clinically informative alternatives.MethodsA systematic search of MEDLINE, Embase, Scopus, and Web of Science was conducted (2015–2025). Study quality was assessed using QUADAS-2 for diagnostic studies and PROBAST for prognostic studies. Due to substantial methodological heterogeneity, meta-analysis was not performed. Findings were synthesized narratively, and diagnostic performance was summarized using forest plots of reported AUC values without statistical pooling.ResultsFrom 3,105 records, 18 studies met the inclusion criteria. The evidence base was dominated by blood-based biomarkers (n = 17). Multi-marker models consistently demonstrated higher diagnostic performance than single analytes, with immune-cell profiling panels and cytokine–clinical parameter models achieving AUC values up to 0.94. In contrast, individual biomarkers generally showed lower performance (e.g., lymphocyte count, AUC = 0.577). Prognostic evidence for blood biomarkers was limited, although plasma D-dimer (AUC ≈ 0.81) and immune-cell profiling models (AUC ≈ 0.72) showed potential for predicting pregnancy outcomes. Only one study evaluated uterine fluid biomarkers, identifying a four-protein panel with promising diagnostic performance, while no eligible studies assessed menstrual fluid.ConclusionFluid-based biomarkers, particularly multi-marker models, may have diagnostic potential in RIF; however, current evidence remains insufficient to support routine clinical implementation. Future research should prioritize prospective validation of blood-based multi-marker models in standardized, euploidy-controlled cohorts, alongside greater investigation of biologically proximal uterine and menstrual biofluids.Systematic review registrationhttps://www.crd.york.ac.uk/PROSPERO/, identifier CRD420251068643.

Preeclampsia, a severe pregnancy-induced disorder unique to humans, affects ∼2%-8% of pregnancies globally. Strong evidence supports placental dysfunction as central to preeclampsia; however, there is inadequate understanding of the precise pathogenesis of preeclampsia. In this study, we present a comprehensive multi-omics analysis of early pregnancy placental biopsies (chorionic villus samples) from pregnancies that later developed preterm/term preeclampsia, compared to normotensive controls. Using an integrative multivariate approach, we uncovered distinct molecular signatures associated with preeclampsia. Preterm preeclampsia was strongly associated with dysregulated lipoprotein metabolism, while term preeclampsia exhibited alterations in inflammatory pathways, Notch/Kit signaling, and ribosome assembly. These results challenge the prevailing notion that term preeclampsia is unrelated to early placental pregnancy dysfunction. To validate our findings, we focused on melanophilin, a gene downregulated in the early pregnancy placenta of term preeclampsia. Melanophilin expression was reduced during cytotrophoblast syncytialization; however, excessive loss disrupted syncytiotrophoblast function, triggering the production of factors known to drive preeclampsia. Our study provides critical insights into the early pregnancy aberrations underlying preterm and term preeclampsia, paving the way for the development of predictive biomarkers and targeted preventative treatments. This work represents a significant step toward unraveling the complex etiology of preeclampsia and improving maternal and perinatal health outcomes.

MOTIVATION:Integrating the knockoff framework with any variable-selection method delivers stringent false discovery rate (FDR) control without recourse to p-values, offering a powerful alternative for differential expression analysis of high-throughput omics datasets. However, existing knockoff generators rely on restrictive modelling assumptions or coarse approximations that often inflate the FDR when applied to real-world data. RESULTS:We introduce Partial Least Squares Knockoff (PLSKO), an efficient, assumption-free generator that remains robust across diverse omics platforms. Our extensive simulations show that PLSKO is the only method to maintain FDR control with sufficient power in complex non-linear settings. Our semi-simulation studies drawn from RNA-seq, proteomics, metabolomics, and microbiome experiments confirm PLSKO generates valid knockoff variables. In pre-eclampsia multi-omics case studies, we combine PLSKO with Aggregation Knockoff to address the randomness of knockoffs and improve power, and demonstrate the method's ability to recover biologically meaningful features. AVAILABILITY AND IMPLEMENTATION:Our proposed algorithm is available on Github (https://github.com/guannan-yang/PLSKO) and Zenodo (https://doi.org/10.5281/zenodo.16879594).

OBJECTIVE Wide-spread endothelial dysfunction is thought to underlie the maternal symptoms of preeclampsia. Endothelial dysfunction is strongly associated with abnormal circulating lipoprotein cholesterol levels. This systematic review aimed to assess whether maternal circulating high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, and very-low-density lipoprotein cholesterol levels were altered before or at the time of preeclampsia diagnosis. This may provide an understanding of the pathogenesis of preeclampsia and the predictive and diagnostic utility of lipoprotein cholesterol levels in distinguishing pregnancies complicated by preeclampsia from normal pregnancies. DATA SOURCES Literature searches were conducted in Ovid MEDLINE, Embase, Cumulative Index of Nursing and Allied Health Literature, and Google Scholar from inception to April 2024 for studies reporting high-density lipoprotein, low-density lipoprotein, and very-low-density lipoprotein levels in normal pregnancies and pregnancies complicated by preeclampsia. STUDY ELIGIBILITY CRITERIA The selected studies included the following: population of pregnant women, exposure to preeclampsia, blood samples collected during a specific trimester of pregnancy, and at least 1 primary outcome (high-density lipoprotein, low-density lipoprotein, or very-low-density lipoprotein). Of note, 2 reviewers were involved in the study selection. The excluded studies included pregnancies complicated by other risk factors for preeclampsia (eg, preexisting hypertension, diabetes mellitus, and obesity) and other pregnancy-related hypertensive disorders (pregnancy-induced hypertension, eclampsia, and hemolysis, elevated liver enzymes, and low platelet count). METHODS The quality of the included studies was evaluated using the Newcastle-Ottawa Scale for case-control, cohort, and cross-sectional studies. RESULTS A total of 41 studies were included. The quality of the studies was generally good. However, 59% of the studies did not control for the gestational age at which the blood samples were collected. No consistent change in high-density lipoprotein or low-density lipoprotein levels was found before preeclampsia diagnosis in the first, second, or third trimesters of pregnancy. Very-low-density lipoprotein was significantly elevated in 2 of 2 studies that reported levels before preeclampsia diagnosis in the late second (>23 weeks of gestation) or third trimester of pregnancy. After preeclampsia diagnosis in the third trimester of pregnancy, very-low-density lipoprotein levels were significantly elevated in 9 of 11 studies, and high-density lipoprotein levels were significantly decreased in 15 of 19 studies. CONCLUSION Very-low-density lipoprotein is highly atherogenic, and its elevation before and at the time of preeclampsia diagnosis suggests a role in the pathogenesis of the endothelial dysfunction associated with preeclampsia. Both very-low-density lipoprotein and high-density lipoprotein show promise as prospective (very-low-density lipoprotein–only) diagnostic biomarkers for preeclampsia.El resumen está disponible en Español al final del artículo.

Late-onset preeclampsia (LOPE) is a major pregnancy complication characterised by hypertension and placental dysfunction, resolving only upon delivery. Here, we show that LOPE placentae undergo accelerated molecular aging, marked by telomere attrition, DNA damage and trophoblast senescence. Using primary placental tissue and trophoblast organoids, we demonstrate oxidative stress as a driver of telomere shortening and angiogenic imbalance. Inflammation did not alter placental aging trajectories. Antioxidant treatment (superoxide dismutase) preserved telomere length, reduced DNA damage and restored angiogenic balance, highlighting oxidative stress as a modifiable determinant of placental aging. We identify reduced expression of telomeric repeat-containing RNAs (TERRAs) as a molecular hallmark of LOPE, and show that antisense oligonucleotide-mediated TERRA depletion exacerbates telomere erosion and senescence. Together, these findings delineate oxidative stress and TERRA loss as mechanisms driving placental decline, establish trophoblast organoids as a tractable model of placental aging, and reveal potential therapeutic avenues for mitigating preeclampsia-associated placental dysfunction.

BackgroundPre-eclampsia is a major cause of perinatal morbidity and mortality worldwide. Late-onset pre-eclampsia (LOP), which results in delivery ≥34 weeks gestation, is the most common type. However, there is a lack of knowledge in its prediction and prevention. Improving our understanding in this area will allow us to have better surveillance of high-risk patients and thus improve clinical outcomes.MethodsA systematic review was performed using a search of articles on PubMed. The search terms were ((late-onset) AND (pre-eclampsia)) AND ((risk factor) OR (risk) OR (prediction) OR (management) OR (prevention)). Primary literature published between 1 January 2013 and 31 December 2023 was included. Human studies assessing the prediction or prevention of late-onset pre-eclampsia were eligible for inclusion.ResultsSixteen articles were included in the final review. The key risk factors identified were Body Mass Index (BMI), chronic hypertension, elevated mean arterial pressures (MAPs), nulliparity, and maternal age. No clinically useful predictive model for LOP was found. Initiating low dose aspirin before 17 weeks gestation in high-risk patients may help reduce the risk of LOP.ConclusionWhile aspirin is a promising preventor of LOP, preventative measures for women not deemed to be at high-risk or measures that can be implemented at a later gestation are required. Biomarkers for LOP need to be identified, and examining large cohorts during the second or third trimester may yield useful results, as this is when the pathogenesis is hypothesized to occur. Biomarkers that identify high-risk LOP patients may also help find preventative measures.

The endometrium undergoes substantial remodeling in each menstrual cycle to become receptive to an implanting embryo. Abnormal endometrial receptivity is one of the major causes of embryo implantation failure and infertility. MicroRNA-124-3p is elevated in both the serum and endometrial tissue of women with chronic endometritis, a condition associated with infertility. MicroRNA-124-3p also has a role in cell adhesion, a key function during receptivity to allow blastocysts to adhere and implant. In this study, we aimed to determine the function of microRNA-124-3p on endometrial epithelial adhesive capacity during receptivity and effect on embryo implantation. Using a unique inducible, uterine epithelial-specific microRNA overexpression mouse model, we demonstrated that elevated uterine epithelial microRNA-124-3p impaired endometrial receptivity by altering genes associated with cell adhesion and polarity. This resulted in embryo implantation failure. Similarly in a second mouse model, increasing microRNA-124-3p expression only in mouse uterine surface (luminal) epithelium impaired receptivity and led to implantation failure. In humans, we demonstrated that microRNA-124-3p was abnormally increased in the endometrial epithelium of women with unexplained infertility during the receptive window. MicroRNA-124-3p overexpression in primary human endometrial epithelial cells (HEECs) impaired primary human embryo trophectoderm attachment in a 3-dimensional culture model of endometrium. Reduction of microRNA-124-3p in HEECs from infertile women normalized HEEC adhesive capacity. Overexpression of microRNA-124-3p or knockdown of its direct target IQGAP1 reduced fertile HEEC adhesion and its ability to lose polarity. Collectively, our data highlight that microRNA-124-3p and its protein targets contribute to endometrial receptivity by altering cell polarity and adhesion.

Endometrial receptivity is crucial for successful embryo implantation during early pregnancy. The human endometrium undergoes remodeling within each menstrual cycle to prepare or become receptive to an implanting blastocyst in the mid-secretory phase. However, the mechanisms behind these changes are not fully understood. Recently, using hormone-treated endometrial organoids to model receptivity, we identified that the transcriptional regulator WD-repeat-containing protein-61 (WDR61) was reduced in organoids derived from infertile women. In this study, we aimed to determine the role of WDR61 in endometrial receptivity. Here, we demonstrated that WDR61 immunolocalizes in the nuclei and cytosol of endometrial glandular epithelium, luminal epithelium, and stroma. The staining intensity of WDR61 was significantly higher during the receptive mid-secretory phase compared to the non-receptive proliferative phase in fertile women. In a functional experiment to model blastocyst adhesion to the endometrial epithelium, we found that adhesion of cytotrophoblast progenitor spheroids was blocked when siRNA was used to knockdown WDR61 in primary endometrial epithelial cells. Similarly, in Ishikawa cells (a receptive human endometrial epithelial cell line), siRNA knockdown of WDR61 significantly reduced the cell adhesive and proliferative capacities. qPCR revealed that WDR61 knockdown reduced expression of key genes involved in receptivity including HOXD10, MMP2, and CD44. Chromatin immunoprecipitation sequencing demonstrated that WDR61 directly targeted 2022 genes in Ishikawa cells, with functions including focal adhesion, intracellular signaling and epithelial-mesenchymal transition. Overall, these findings suggest that WDR61 promotes endometrial receptivity by modulating epithelial cell focal adhesions, proliferation, and epithelial-mesenchymal transition.

Introduction A healthy pregnancy requires successful blastocyst implantation into an adequately prepared or ‘receptive’ endometrium. Decidualization of uterine endometrial stromal fibroblast cells (hESF) is critical for the establishment of a healthy pregnancy. microRNAs (miRs) are critical regulators of cellular function that can be released by a donor cell to influence the physiological state of recipient cells. We aimed to determine how decidualization affects hESF miR release and investigated the function of one decidualization regulated miR, miR-19b-3p, previously shown to be associated with recurrent pregnancy loss. Method miR release by hESF was determined by miR microarray on culture media from hESF decidualized in vitro for 3 and 14 days by treatment with oestradiol and medroxyprogesterone acetate. Cellular and whole endometrial/decidual tissue miR expression was quantified by qPCR and localized by in situ hybridization. The function of miR-19b-3p in HTR8/Svneo trophoblast cells was investigated using real time cell analysis (xCELLigence) and gene expression qPCR. Results From our miR screen we found that essentially all hESF miR release was reduced following in vitro decidualization, significantly so for miR-17-5p, miR-21-3p, miR-34c-3p, miR-106b-5p, miR-138-5p, miR-296-5p, miR-323a-3p, miR-342-3p, miR-491-5p, miR-503-5p and miR-542-5p. qPCR demonstrated that miR-19b-3p, 181a-2-3p and miR-409-5p likewise showed a significant reduction in culture media following decidualization but no change was found in cellular miR expression following decidualization. In situ hybridization localized miR-19b-3p to epithelial and stromal cells in the endometrium and qPCR identified that miR-19b-3p was significantly elevated in the cycling endometrium of patients with a history of early pregnancy loss compared to normally fertile controls. Functionally, overexpression of miR-19b-3p significantly reduced HTR8/Svneo trophoblast proliferation and increased HOXA9 expression. Discussion Our data demonstrates that decidualization represses miR release by hESFs and overexpression of miR-19b-3p was found in endometrial tissue from patients with a history of early pregnancy loss. miR-19b-3p impaired HTR8/Svneo proliferation implying a role in trophoblast function. Overall we speculate that miR release by hESF may regulate other cell types within the decidua and that appropriate release of miRs by decidualized hESF is essential for healthy implantation and placentation.

Pre-eclampsia is a life-threatening disease of pregnancy unique to humans and a leading cause of maternal and neonatal morbidity and mortality. Women who survive pre-eclampsia have reduced life expectancy, with increased risks of stroke, cardiovascular disease and diabetes, while babies from a pre-eclamptic pregnancy have increased risks of preterm birth, perinatal death and neurodevelopmental disability and cardiovascular and metabolic disease later in life. Pre-eclampsia is a complex multisystem disease, diagnosed by sudden-onset hypertension (>20 weeks of gestation) and at least one other associated complication, including proteinuria, maternal organ dysfunction or uteroplacental dysfunction. Pre-eclampsia is found only when a placenta is or was recently present and is classified as preterm (delivery <37 weeks of gestation), term (delivery ≥37 weeks of gestation) and postpartum pre-eclampsia. The maternal syndrome of pre-eclampsia is driven by a dysfunctional placenta, which releases factors into maternal blood causing systemic inflammation and widespread maternal endothelial dysfunction. Available treatments target maternal hypertension and seizures, but the only 'cure' for pre-eclampsia is delivery of the dysfunctional placenta and baby, often prematurely. Despite decades of research, the aetiology of pre-eclampsia, particularly of term and postpartum pre-eclampsia, remains poorly defined. Significant advances have been made in the prediction and prevention of preterm pre-eclampsia, which is predicted in early pregnancy through combined screening and is prevented with daily low-dose aspirin, starting before 16 weeks of gestation. By contrast, the prediction of term and postpartum pre-eclampsia is limited and there are no preventive treatments. Future research must investigate the pathogenesis of pre-eclampsia, in particular of term and postpartum pre-eclampsia, and evaluate new prognostic tests and treatments in adequately powered clinical trials.

Pre-eclampsia is a life-threatening disease of pregnancy unique to humans and a leading cause of maternal and neonatal morbidity and mortality. Women who survive pre-eclampsia have reduced life expectancy, with increased risks of stroke, cardiovascular disease and diabetes, while babies from a pre-eclamptic pregnancy have increased risks of preterm birth, perinatal death and neurodevelopmental disability and cardiovascular and metabolic disease later in life. Pre-eclampsia is a complex multisystem disease, diagnosed by sudden-onset hypertension (>20 weeks of gestation) and at least one other associated complication, including proteinuria, maternal organ dysfunction or uteroplacental dysfunction. Pre-eclampsia is found only when a placenta is or was recently present and is classified as preterm (delivery <37 weeks of gestation), term (delivery ≥37 weeks of gestation) and postpartum pre-eclampsia. The maternal syndrome of pre-eclampsia is driven by a dysfunctional placenta, which releases factors into maternal blood causing systemic inflammation and widespread maternal endothelial dysfunction. Available treatments target maternal hypertension and seizures, but the only ‘cure’ for pre-eclampsia is delivery of the dysfunctional placenta and baby, often prematurely. Despite decades of research, the aetiology of pre-eclampsia, particularly of term and postpartum pre-eclampsia, remains poorly defined. Significant advances have been made in the prediction and prevention of preterm pre-eclampsia, which is predicted in early pregnancy through combined screening and is prevented with daily low-dose aspirin, starting before 16 weeks of gestation. By contrast, the prediction of term and postpartum pre-eclampsia is limited and there are no preventive treatments. Future research must investigate the pathogenesis of pre-eclampsia, in particular of term and postpartum pre-eclampsia, and evaluate new prognostic tests and treatments in adequately powered clinical trials. Pre-eclampsia is a life-threatening disease of pregnancy and a leading cause of maternal and neonatal morbidity and mortality. This Primer by Dimitriadis and colleagues summarizes the epidemiology, mechanisms, diagnosis and treatment of pre-eclampsia, and discusses patient quality of life and open research questions for this condition.

This review leads the 2023 Call for Papers in MHR: 'Cyclical function of the female reproductive tract' and will outline the complex and fascinating changes that take place in the reproductive tract during the menstrual cycle. We will also explore associated reproductive tract abnormalities that impact or are impacted by the menstrual cycle. Between menarche and menopause, women and people who menstruate living in high-income countries can expect to experience ∼450 menstrual cycles. The primary function of the menstrual cycle is to prepare the reproductive system for pregnancy in the event of fertilization. In the absence of pregnancy, ovarian hormone levels fall, triggering the end of the menstrual cycle and onset of menstruation. We have chosen to exclude the ovaries and focus on the other structures that make up the reproductive tract: uterine tubes, endometrium, myometrium, and cervix, which also functionally change in response to fluctuations in ovarian hormone production across the menstrual cycle. This inaugural paper for the 2023 MHR special collection will discuss our current understanding of the normal physiological processes involved in uterine cyclicity (limited specifically to the uterine tubes, endometrium, myometrium, and cervix) in humans, and other mammals where relevant. We will emphasize where knowledge gaps exist and highlight the impact that reproductive tract and uterine cycle perturbations have on health and fertility.

Female cancer survivors are significantly more likely to experience infertility than the general population. It is well established that chemotherapy and radiotherapy can damage the ovary and compromise fertility, yet the ability of cancer treatments to induce uterine damage, and the underlying mechanisms, have been understudied. Here, we show that in mice total-body γ-irradiation (TBI) induced extensive DNA damage and apoptosis in uterine cells. We then transferred healthy donor embryos into ovariectomized adolescent female mice that were previously exposed to TBI to study the impacts of radiotherapy on the uterus independent from effects to ovarian endocrine function. Following TBI, embryo attachment and implantation were unaffected, but fetal resorption was evident at midgestation in 100% of dams, suggesting failed placental development. Consistent with this hypothesis, TBI impaired the decidual response in mice and primary human endometrial stromal cells. TBI also caused uterine artery endothelial dysfunction, likely preventing adequate blood vessel remodeling in early pregnancy. Notably, when pro-apoptotic protein Puma-deficient (Puma–/–) mice were exposed to TBI, apoptosis within the uterus was prevented, and decidualization, vascular function, and pregnancy were restored, identifying PUMA-mediated apoptosis as a key mechanism. Collectively, these data show that TBI damages the uterus and compromises pregnancy success, suggesting that optimal fertility preservation during radiotherapy may require protection of both the ovaries and uterus. In this regard, inhibition of PUMA may represent a potential fertility preservation strategy.

Pre-eclampsia is a life-threatening disease of pregnancy unique to humans and a leading cause of maternal and neonatal morbidity and mortality. Women who survive pre-eclampsia have reduced life expectancy, with increased risks of stroke, cardiovascular disease and diabetes, while babies from a pre-eclamptic pregnancy have increased risks of preterm birth, perinatal death and neurodevelopmental disability and cardiovascular and metabolic disease later in life. Pre-eclampsia is a complex multisystem disease, diagnosed by sudden-onset hypertension (>20 weeks of gestation) and at least one other associated complication, including proteinuria, maternal organ dysfunction or uteroplacental dysfunction. Pre-eclampsia is found only when a placenta is or was recently present and is classified as preterm (delivery <37 weeks of gestation), term (delivery >= 37 weeks of gestation) and postpartum pre-eclampsia. The maternal syndrome of pre-eclampsia is driven by a dysfunctional placenta, which releases factors into maternal blood causing systemic inflammation and widespread maternal endothelial dysfunction. Available treatments target maternal hypertension and seizures, but the only 'cure' for pre-eclampsia is delivery of the dysfunctional placenta and baby, often prematurely. Despite decades of research, the aetiology of pre-eclampsia, particularly of term and postpartum pre-eclampsia, remains poorly defined. Significant advances have been made in the prediction and prevention of preterm pre-eclampsia, which is predicted in early pregnancy through combined screening and is prevented with daily low-dose aspirin, starting before 16 weeks of gestation. By contrast, the prediction of term and postpartum pre-eclampsia is limited and there are no preventive treatments. Future research must investigate the pathogenesis of pre-eclampsia, in particular of term and postpartum pre-eclampsia, and evaluate new prognostic tests and treatments in adequately powered clinical trials. Pre-eclampsia is a life-threatening disease of pregnancy and a leading cause of maternal and neonatal morbidity and mortality. This Primer by Dimitriadis and colleagues summarizes the epidemiology, mechanisms, diagnosis and treatment of pre-eclampsia, and discusses patient quality of life and open research questions for this condition.