Search Results (118)

Recurrent pregnancy loss (RPL) is a multifactorial reproductive disorder with important genetic, endocrine, immune, and metabolic determinants. Growing evidence links vitamin D deficiency and vitamin D receptor (VDR) gene polymorphisms to pregnancy complications, including RPL. A narrative review was conducted via a literature search in major databases: PubMed, EMBASE, Scopus, and Web of Science from January 2010 to January 2026, which synthesized observational studies on maternal 25-hydroxyvitamin D [25(OH)D] status and/or VDR polymorphisms in RPL, with predefined eligibility criteria and qualitative risk-of-bias assessment. Most studies focused on FokI (rs2228570) and the 3′ regulatory block BsmI/ApaI/TaqI. FokI is the most extensively studied VDR variant in RPL and showed the most consistent directional association compared with other variants, particularly in Asian and Middle Eastern populations, though the effect varied by study design, ancestry, and covariate adjustment. Contrary to that, investigations of BsmI/ApaI/TaqI loci were not consistent due to ancestry-specific linkage disequilibrium (LD). Genotype and vitamin D interaction effects were scarcely studied, with stratified analyses indicating a more significant genotype effect under vitamin D deficiency. From clinical practice perspectives, VDR polymorphisms may explain why some patients with RPL have a poor response to standard vitamin D supplementation. Women with the FokI f allele polymorphism associated with lower VDR activity require higher vitamin D dosing or earlier immunomodulatory support to achieve adequate endometrial receptivity. VDR variation, particularly FokI, may contribute to RPL susceptibility within an endocrine–immune–metabolic framework. Clinical translation will require standardized RPL definitions, concurrent 25(OH)D assessment, robust control for confounders, and analytical models that account for gene–environment interactions. Full article

Objectives: To evaluate the presence and dominance of Lactobacillus in the endometrial microbiome and their age-related associations in a large group of Bulgarian patients with recurrent implantation failure (RIF) and recurrent pregnancy loss (RPL) who attend our clinic. Methods: This retrospective study included 199 patients (mean age: 35.69 ± 5.16) with RIF (n = 103) and RPL (n = 96) who visited our fertility clinic between October 2019 and November 2022. Endometrial samples were analyzed using real-time PCR for target DNA sequences. Results: Overall, 62.8% (n = 125) exhibited an absence of Lactobacilli in their endometrial samples, with 63.1% (n = 65) of the RIF group and 62.5% (n = 60) of the RPL group showing a lack of Lactobacilli, with no statistically significant difference between the groups (p = 0.926). A Lactobacillus-dominant microbiome was found in 23.6% of the entire cohort (n = 47), 25.2% of the RIF group (n = 26) and 21.9% of the RPL group (n = 21). A reduced abundance of Lactobacilli was identified in 13.5% of the cohort (n = 27), though to differing degrees. There was no significant relationship between the abundance of Lactobacilli and belonging to the RIF or RPL group. A statistically significant difference was found in the mean age of two groups in cases with a Lactobacillus-dominant microbiome (mean age of 36.4 ± 4.8 years in the RIF group and 32.5 ± 3.5 years in the RPL group) (p = 0.004). Conclusions: Our findings demonstrate a high prevalence of non-Lactobacillus-dominant microbiomes in a large group of Bulgarian patients with RIF and RPL and significant age-related Lactobacillus changes in the microbiome of patients with RPL. These results point to the potential role of the uterine microbiome and support the need for further prospective studies, especially in cases of advanced maternal age. Full article

Background: Recurrent pregnancy loss (RPL) remains etiologically unexplained in 40–50% of cases following standard diagnostic workup. Non-criteria antiphospholipid antibodies (non-criteria aPL) are increasingly considered potential markers of seronegative obstetric antiphospholipid syndrome (APS); however, their diagnostic value in this clinical setting requires further investigation. Objective: To assess the diagnostic value of non-criteria aPL in women with RPL and to construct an exploratory immunological scoring model for diagnostic stratification. Methods: Antiphospholipid antibody detection was performed using a single-measurement semi-quantitative line immunoblot assay (Anti-Phospholipid 10 Dot, Generic Assays, Germany). Statistical analysis included χ², Fisher’s exact test, Mann–Whitney U test, binary logistic regression, and ROC analysis. Results: Statistically significant associations with RPL were observed for anti-prothrombin antibodies (OR = 11.1; 95% CI 1.8–68.0; p = 0.022 [Haldane–Anscombe correction]), anti-annexin V (OR = 4.28; 95% CI 1.18–15.6; p = 0.023), and anti-β₂GP I (OR = 3.31; 95% CI 1.18–9.28; p = 0.019). The exploratory composite immunological score demonstrated moderate discriminatory performance (AUC = 0.701; 95% CI 0.588–0.814; p = 0.005). The overall logistic regression model was statistically significant (χ² = 8.564; p = 0.036), although none of the individual predictors retained independent significance, indicating a contribution of cumulative immunological burden rather than any single marker. Conclusions: In this single-center cross-sectional study, non-criteria aPL were frequently detected in women with RPL and were statistically associated with the condition. The findings should be interpreted as hypothesis-generating only, given the cross-sectional design, single-measurement immunoblot, small control group, and absence of external validation. Confirmation in larger prospective multicenter cohorts using ELISA-based assays with the internationally recommended 12-week repeat measurement is required before any clinical implementation. Full article

Background: Chronic endometritis (CE) is a subtle, often asymptomatic endometrial inflammation marked by CD138⁺ plasma cell infiltration and linked to recurrent implantation failure (RIF), recurrent pregnancy loss (RPL), and unexplained infertility. Emerging evidence implicates endometrial microbiome dysbiosis in CE. Objective: To systematically review and conduct meta-analysis on the association between CE and endometrial microbiome alterations and their reproductive implications. Methods: We searched MEDLINE, Embase, Web of Science, Scopus, Cochrane CENTRAL, and Google Scholar for studies diagnosing CE via CD138 immunostaining, assessing microbiota with molecular techniques. Data extraction, quality assessment, and meta-analysis were performed. Results: Twenty-two studies including 4022 women were analyzed. CE was associated with reduced prevalence of Lactobacillus-dominated microbiota and increased detection of non-Lactobacillus species, particularly Streptococcus spp., Enterococcus spp., Escherichia coli, Staphylococcus spp., Ureaplasma spp., and Gardnerella vaginalis. In the meta-analysis (2947 women), Enterococcus spp. and Ureaplasma spp. were significantly more prevalent in women with CE, whereas Streptococcus spp., E. coli, Staphylococcus spp. and G. vaginalis showed non-significant trends. Only E. coli and Streptococcus spp. showed significant heterogeneity between-studies. Conclusions: CE is linked to microbial dysbiosis with reduced Lactobacillus dominance and enrichment of potentially pathogenic taxa, notably Enterococcus and Ureaplasma spp. These findings suggest that the endometrial microbiome contributes to chronic inflammation and adverse reproductive outcomes, yet heterogeneity and limited evidence call for standardized diagnostics and robust trials before clinical implementation. Full article

Background/Objectives: To evaluate the diagnostic yield of phenotype-guided cytogenetic and targeted molecular genetic testing in patients referred for infertility and reproductive disorders within a tertiary medical genetics referral pathway. Methods: This retrospective study included 900 consecutive patients (473 males, 427 females) referred to a tertiary medical genetics center between January 2020 and December 2024. Conventional karyotyping was performed in all patients. Additional targeted molecular tests were applied based on clinical indication: Y chromosome microdeletion analysis in azoospermia or oligospermia, CFTR sequencing in suspected congenital bilateral absence of the vas deferens, and F2/F5 genotyping in recurrent pregnancy loss (RPL). Diagnostic yield was analyzed in a predefined subgroup of 566 patients with RPL, unexplained infertility, azoospermia, or oligospermia; remaining referrals were included in descriptive cytogenetic analyses only. Results: Chromosomal abnormalities were identified in 3.22% (29/900) of the total cohort and in 5.12% (29/566) of the diagnostic-yield cohort. Targeted testing yields were 3.75% (6/160) for Y chromosome microdeletions, 9.38% (3/32) for CFTR variants, and 3.31% (4/121) for F2/F5 variants. Diagnostic yield varied markedly by phenotype, being highest in azoospermia (33.3%), followed by oligospermia (6.6%), RPL (5.3%), and unexplained infertility (3.1%). In unexplained infertility, all chromosomal abnormalities were detected in female patients. Conclusions: In a tertiary referral setting, phenotype-guided genetic testing provides the greatest diagnostic value in well-defined infertility phenotypes, particularly azoospermia. Lower yields in other referral groups support a targeted, indication-based approach to genetic evaluation and highlight the need for advanced genomic strategies in persistently unexplained cases. Full article

Anti-β2GPI/HLA-DR antibody, chronic endometritis (CE), and endometrial dysbiosis are likely to be associated with the etiologies of recurrent pregnancy loss (RPL). This prospective cohort study aimed to investigate these new risk factors together with conventional causes for RPL, and to evaluate pregnancy outcomes in women individually treated. A total of 87 women with RPL underwent conventional assessment together with anti-β2GPI/HLA-DR antibody measurements, CD138 immunohistochemistry for CE, and 16S rRNA sequence analysis for endometrial microbiome. Women with anti-β2GPI/HLA-DR antibody, CE, and endometrial dysbiosis received low-dose aspirin and heparin, antibiotics, and probiotics, respectively. Pregnancy outcomes of the participants were assessed. Anti-β2GPI/HLA-DR antibody, CE, non-Lactobacillus-dominant microbiome (NLDM)-1 (Lactobacillus + Bifidobacterium < 80%), and NLDM-2 (Lactobacillus without iners + Bifidobacterium < 80%) were detected in 16 (18.4%), 22 (25.3%), 27 (31.0%), and 46 (52.8%) women, respectively. Based on conventional assessment, 65.5% of women with RPL were classified as unexplained etiology; however, the percentage reduced to 16.1% when these new tests were assessed together. All 9 pregnancies with anti-β2GPI/HLA-DR antibody, 13 (92.9%) of 14 pregnancies with CE, and 24 (92.3%) of 26 pregnancies with NLDM-2 resulted in live birth. Assessment of these new tests may be clinically useful for reducing the proportion of unexplained RPL, and for providing high live birth rates if women receive relevant treatments. Full article

Background: Recurrent pregnancy loss (RPL) and infertility are associated with significant psychological morbidity, including stress, anxiety, and depression. While these impacts are well-documented globally, their prevalence and severity in the Omani population remain unexplored. This study investigates the mental health outcomes of Omani women with RPL and infertility compared to fertile controls. Objectives: The objectives of this study are to assess the prevalence of stress, anxiety, and depression in women with recurrent pregnancy loss (RPL) and infertility and compare these rates to women with no fertility concerns in an Omani population. Design: This is a prospective, cross-sectional study. Setting: This study’s setting consisted of Sultan Qaboos University Hospital and Royal Hospital in Muscat, Oman. Participants: This study included 111 women with RPL, 131 women with infertility, and 210 antenatal controls with no fertility issues. Interventions: No clinical interventions were administered as this was an observational study. Participants completed validated psychological assessments (DASS-42 and BDI-II). Primary and secondary outcome measures: Primary outcomes were the prevalence rates of stress, anxiety, and depression assessed using DASS-42 and BDI-II. Secondary outcomes included sociodemographic correlates and risk factors Results: This study included 111 women in the RPL group, 131 in the infertility group, and 210 controls. Among RPL patients, 31% reported stress, ranging from mild to extremely severe, while 35.9% of infertility patients reported stress, compared to 17.1% in the control group (p = 0.003). Anxiety was present in 45% of RPL patients, 45.5% of infertility patients, and 28.1% of controls (p = 0.019). Depression, measured by DASS-42, was the most prevalent in the RPL group (34.2%), followed by the infertility group (33.6%) and controls (13.8%) (p < 0.001). Similar results were observed with BDI-II, with depression rates of 23.4% in the RPL group, 19.1% in the infertility group, and 7.6% in controls (p = 0.02). Conclusions: Women with RPL and infertility in Oman experience significantly higher levels of stress, anxiety, and depression compared to women without fertility concerns. This study did not assess the mental health of male partners, highlighting the need for further research on the psychological impact on both partners. Future studies should focus on developing psychological support interventions and evaluating their impact on patient outcomes. Full article

Recurrent pregnancy loss (RPL) is defined as the loss of two or more pregnancies before the 22nd gestational week and affects 10–15% of clinical pregnancies. Despite extensive diagnostics, over 50% of RPL cases remain unexplained, suggesting an important role for immunological mechanisms. Sex hormones (SH) are key regulators of immune responses during pregnancy; however, their influence on immune checkpoint proteins (ICPs) is poorly understood. This study evaluated the effects of progesterone, β-estradiol, and dihydrotestosterone (DHT) on ICP expression on immune cells, including Treg, NK, NKT, TC, Th, and T cells, collected from pregnant women and patients with unexplained RPL (uRPL). Peripheral blood mononuclear cells from 20 pregnant women and 20 uRPL patients were cultured for 48 h with SH. The expression of the first generation of ICPs—PD-1 and TIM-3—and the second—LAG-3, TIGIT, and VISTA—on T, NK, and NKT cells was analyzed by the flow cytometry method. In pregnant women, SH exerted modest effects, with DHT increasing VISTA and LAG-3 expression, while progesterone and estradiol mainly upregulated LAG-3 and TIM-3 on cytotoxic cells. In contrast, uRPL immune cells showed pronounced SH sensitivity, characterized by increased TIM-3 and VISTA expression and reduced TIGIT expression, particularly after DHT stimulation. In conclusion, SH modulates ICP expression in a cell-specific manner, with stronger effects observed in uRPL patients’ lymphocytes. These findings highlight a potential role for hormonal and ICP-targeted strategies in RPL management. Full article

Background: Despite significant advances in genetics, immunology, and endometrial research, the underlying cause of nearly half of recurrent pregnancy loss (RPL) cases remains unknown. This highlights the limitations of conventional diagnostic approaches and underscores the need for methods that can detect complex, subtle biological patterns. Objectives: To summarize and critically assess how artificial intelligence (AI) is changing our knowledge of, ability to predict, and future therapeutic management of RPL, with a focus on machine learning (ML) approaches that identify latent biological pathways and multifactorial contributors to pregnancy loss. Methods: This narrative review summarizes contemporary research on AI applications in reproductive medicine. Research using imaging, proteomic, genomic, clinical, and multi-omics information to create predictive or mechanistic models associated with RPL provided evidence. Results: AI-based approaches are increasingly demonstrating the ability to detect complex interactions among environmental, immunological, biochemical, and genetic factors associated with RPL. ML and deep learning (DL) models enhance prognostic accuracy, identify novel candidate biomarkers, and provide insights into the systemic and molecular mechanisms underlying pregnancy loss. Integrating heterogeneous data through AI supports the development of personalized reproductive profiles and can improve prediction and counseling. Conclusions: AI has the potential to improve both personalized prediction and mechanistic understanding of RPL. However, clinical translation is currently hampered by a number of important issues, including small and diverse datasets, conflicting diagnostic definitions, limited external validation, and a lack of prospective clinical trials. To responsibly integrate AI tools into reproductive care, these limitations must be addressed. Full article

Unexplained infertility and idiopathic recurrent pregnancy loss (RPL) have a prevalence of 1–5% of women of reproductive age in different populations. There are a few reports comparing the circulating immune cell populations and subpopulations in these medical entities in admixed populations. The study aimed to assess the different leukocyte, mononuclear cell populations, and T lymphocyte subpopulations and HLADR expression, as a marker of activation, in an admixed group of Venezuelan women: 80 controls, 73 women with RPL (53 primary, 20 secondary), and 26 infertile (20 primary, six secondary). Endometriosis was clinically ruled out in all patients and controls. Total leukocytes were 10–12% higher (p < 0.0001) in the infertile group, while neutrophils were 11% in the infertility group (p < 0.0001). In contrast, lymphocytes, CD3CD4 cells, NK cells, and HLADR+ cells were elevated (10–15, 18–22, 50–60, and 700–800% increase, respectively) in all patient groups. Changes in B cell numbers and monocyte counts were also observed. HLADR expression was significantly increased (p < 0.0001) in T cells, CD56+ cells, and monocytes of all patients. In infertile patients, a correlation was recorded between HLADR and T memory cells. Marked differences in peripheral blood leukocytes, NK cells, monocytes, T-cell populations, and HLADR suggest a proinflammatory effect. HLADR can be used as a simple biomarker to monitor pharmacological treatment in these patients. Full article

Background: Recurrent pregnancy loss (RPL) is a multifactorial condition in which genetic variants associated with thrombophilia may contribute to altered coagulation and adverse pregnancy outcomes. Objective: This study aimed to investigate the association between thrombophilia-related single nucleotide variants (SNVs) and coagulation-related metabolites in a cohort of Mexican women with RPL. Methods: A retrospective and descriptive design was conducted including 105 women with at least two consecutive miscarriages and with a multidisciplinary approach that included a thrombophilia-associated SNVs panel. Peripheral blood samples were collected after fasting for biochemical and molecular analyses. Genotyping of thrombophilia-associated SNVs was performed using real-time PCR with custom-designed TaqMan probes on a Rotor-Gene Q platform, including variants in AGT (rs4762, rs699), F7 (rs6046), FGB (rs1800790), MTR (rs1805087), MTRR (rs1801394), MTHFR (rs1801133, rs1801131), F2 (rs1799963), F5 (rs6025), SERPINE1 (rs1799889), F12 (rs1801020), and F13A1 (rs5985) genes. Coagulation parameters evaluated were folic acid, cobalamin, fibrinogen, D-dimer, homocysteine, antithrombin III activity, thrombin time (TT), prothrombin time (PT), activated partial thromboplastin time (aPTT), international normalized ratio (INR), and Factor XII activity. Results: Significant differences were found in INR values across F7-rs6046 genotypes (p = 0.006), with an additive model showing a mean difference of 0.05 (p = 0.0009). The F12-rs1801020 variant was strongly associated with Factor XII activity (p = 0.002) and aPTT (p = 0.045). Conclusions: These findings indicate that F7-rs6046 and F12-rs1801020 genotypes influence specific coagulation parameters, suggesting that certain thrombophilia-associated SNVs may modulate the hemostatic profile in Mexican women with RPL and contribute to personalized risk assessment in reproductive medicine. Full article

Recurrent pregnancy loss (RPL), also termed recurrent spontaneous abortion, is defined as the failure of ≥2 consecutive pregnancies before 20 weeks of gestation. Approximately 5% of pregnant couples experience RPL. The hyaluronan-binding protein 2 (HABP2) gene is involved in coagulation and plays an important role during pregnancy. In >50% of RPLs, the etiology remains unexplained. We collected 765 blood samples from 388 female RPL patients and 377 healthy female controls. To investigate the relationships between HABP2 polymorphisms and RPL, we examined six HABP2 variants (rs3832698 A>del, rs10885478 G>A, rs932650 T>C, rs7923349 G>T, rs1157916 G>A, and rs2240879 T>C) to clarify their association with RPL risk. The rs2240879 CC genotype was significantly associated with an increased RPL risk (p = 0.028). In haplotype analysis, the combination of rs3832698 del and rs2240879 T (del-T) was associated with elevated risk (p = 0.043); this risk persisted in combinations with additional polymorphisms (rs3832698 A>del, rs10885478 G>A, rs932650 T>C, rs7923349 G>T; del-A-T-T, p < 0.001; rs3832698 A>del, rs10885478 G>A, rs932650 T>C, rs7923349 G>T, rs1157916 G>A, rs2240879 T>C; del-A-C-T-G-T, p = 0.024). The rs3832698 and rs1157916 genotypes were significantly associated with prothrombin time (p = 0.020 and p = 0.012, respectively). We identified associations between HABP2 polymorphisms and RPL; rs2240879 was linked to an increased RPL risk. Additionally, rs3832698 was associated with an altered prothrombin time. These findings suggest that HABP2 represents a biomarker for RPL susceptibility. Full article

Background/Objectives: Recurrent pregnancy loss (RPL) is one of the most challenging conditions in reproductive medicine, particularly when no identifiable cause can be determined after diagnostic evaluation. Although the role of immunological dysregulation has been hypothesized, the implementation of immunotherapies in clinical practice is controversial due to inconsistent findings and methodological heterogeneity across studies. This systematic review aims to provide an overview of the main characteristics of existing research on the role of immunological interventions in relation to In Vitro Fertilization (IVF) outcomes in women with RPL. Given the marked inter-individual variability in immunological mechanisms among affected women, evaluating these treatments may help identify future directions for personalized reproductive medicine. Methods: A comprehensive bibliographic search was systematically conducted from inception to October 2025 across databases, including Medline, Embase, Scopus, the Cochrane Database of Systematic Reviews, and ClinicalTrials.gov. Studies were included if they evaluated the efficacy of immunological treatments in women with unexplained RPL, comparing IVF outcomes between case and control groups. Results: Six cohort studies were included, four retrospective and two prospective. The immunological treatments investigated were granulocyte colony-stimulating factor (G-CSF), intravenous intralipid (with or without prednisolone), and lymphocyte immunization therapy (LIT). Despite some promising results, particularly for G-CSF and LIT, the studies were limited by small sample sizes, heterogeneous diagnostic criteria for RPL, and inconsistent treatment protocols. Furthermore, not all IVF outcomes, such as implantation and biochemical pregnancy rates, were reported. Conclusions: Current evidence is insufficient to support the use of immunotherapy in clinical practice for improving IVF outcomes in women with unexplained RPL. The variability in study design, patient selection, and immunotherapy regimens hinders the ability to draw firm conclusions. Well-designed randomized controlled trials with standardized definitions and outcome measures are needed to determine whether and for whom immunological treatments may offer clinical benefit. Full article

Killer-cell immunoglobulin-like receptors (KIRs) play a crucial role in the cytotoxic activity of natural killer (NK) cells, encompassing both inhibitory and activating types. A higher ratio of cytotoxic to inhibitory receptors may harm successful pregnancies by disrupting the uterine environment. Ongoing debates surround the impact of KIR gene variations on recurrent pregnancy loss (RPL) and infertility across populations. This study aimed to explore KIR gene polymorphisms in RPL and infertility among the Venezuelan admixed population. The Venezuelan population exhibits a genetic mix of Caucasian, African, and local Amerindian ancestry, distinguishing it from other Latin American admixed populations. This study included 100 controls and 86 patients: 73 women with idiopathic RPL (53 primary and 20 secondary) and 13 infertile patients (4 primary and 9 secondary). The frequency of activating receptors KIR2DS2 and KIR2DS3 was significantly lower (p < 0.05) in the whole patient group compared to controls. However, when analyzing the haplotypes and genotypes, the significance between patients and controls was lost. When comparing RPL and infertile patients, KIR2DS2, KIR2DL3, 2DL5, and 3DL1 were significantly less frequent in infertile women. In infertile women, KIR2DS3 frequency was increased compared to controls and RPL. The results suggest that the frequency of inhibitory receptors may differentiate patients with RPL and infertility. Further studies should ascertain the expression and function of KIRs in uterine NK cells in patients with RPL and infertility. Full article

The immunological factor of sterility, specifically the abnormal count and activity of uterine NK (uNK) cells, may represent one of the potential contributors affecting specific subgroups of sterile couples undergoing assisted reproductive treatment (ART). Therefore, the primary purpose of the present paper was to assess uNK cell count. A total of 387 endometrial biopsies from patients with recurrent implantation failure (RIF) or recurrent pregnancy loss (RPL) were analyzed to identify abnormalities in uNK cell count, using immunohistopathological evaluation. ANOVA analysis revealed a strong association with factor 0.161 with p-value < 0.01, indicating that higher uNK cell count is associated with the presence of clusters (multicellular aggregates of uNK cells). These results suggest that the formation of clusters and the spatial distribution of uNK cells are significant factors in the context of the aforementioned clinical questions. However, the actual translational potential to clinical practice has not yet been established due to several challenges, namely: 1. the constantly changing definitions and diagnostic criteria for RIF and RPL, 2. varying sampling approaches for uNK cells, and 3. the historical lack of clear differentiation between uterine and peripheral NK cells. When all these issues are resolved, the observed tendency of uNK cells to form clusters will need to be a central focus of future investigations addressing RIF and RPL, thus improving ART outcomes. Full article