Altered Endometrial Microbiota Profile Is Associated With Poor Endometrial Receptivity of Repeated Implantation Failure

PURPOSE

To gain insight into the endometrial pathophysiology of unexplained repeated implantation failure (RIF), we examined the characteristics of genital tract microbiota and explored the correlation between the microbiota and endometrial receptivity.

METHODS

Vaginal secretion (VS) and endometrial biopsy (EB) samples were collected from patients with RIF (RIF group, n = 32) and those with infertility who had achieved pregnancy during their initial embryo transfer cycle (control group, n = 18). 16S ribosomal RNA sequencing and quantitative PCR were performed to characterize the microbiota of the two groups. Spearman's correlation analysis was performed to determine the relationship between endometrial receptivity markers and endometrial microbiota.

RESULTS

Endometrial microbiota exhibited distinct characteristics from vaginal microbiota, with a higher alpha-diversity. Alpha-diversity of the endometrial microbiota was higher in the RIF group than in the control group. Compared with the control group, the RIF group had a significant decrease in endometrial Lactobacillus abundance and an increase in Gardnerella and Acinetobacter abundances. The expression levels of endometrial receptivity markers, including homeobox A11, integrin αvβ3, leukemia inhibitor factor, matrix metalloproteinase-9, and vascular endothelial growth factor, were lower in the RIF group than in the control group. Moreover, the expression levels of these markers were correlated with endometrial Lactobacillus, Gardnerella, and Acinetobacter abundances.

CONCLUSION

RIF is characterized by endometrial microbiota dysbiosis and poor endometrial receptivity. Moreover, abnormal endometrial microbiota is associated with impaired endometrial receptivity, which may be a potential cause of unexplained RIF.

Utility of culture and molecular methods using AllplexTM Bacterial Vaginosis Plus Assay (SeegeneⓇ) as a tool for endometriosis, infertility and recurrent pregnancy loss diagnosis

Endometriosis, infertility, or recurrent pregnancy loss (RPL) are entities characterised by a decrease in Lactobacillus spp. and an increase in bacterial vaginosis-associated bacteria, (BVAV) according with 16S rRNA sequencing studies. However, the use of nucleic acid amplification tests (NAAT) as a tool for diagnosis algorithms is unknown. Seventy-four patients were included, with a median age of 36.5 years old (IQR: 34-39) including infertility (n=31), endometriosis (n=25), or RPL (n=18), for culturing and NAAT using the Allplex™ Bacterial Vaginosis Plus (ABVP) assay (SeegeneⓇ) with endometrial samples. The objective was determining the utility of ABVP assay for diagnosing the entities. Forty-six microorganisms were isolated from 31 out of 74 patients (41.9 %). Twenty-five endometrial samples (33.8 %) were positive for some targets included in the ABVP-assay, with median Ct value ∼37 (IQR: 31.3-37.1) and Qt value 1.43 Log10copies/reaction (IQR:1.1-2.6). For Lactobacillus species, sensitivity and specificity were 80 % and 84 %, respectively. Gardnerella vaginalis, 63.6 % and 95.7 %. No significant increase in BVAV was detected in any of the gynaecological entities. The ABVP and culture based algorithm did not show utility as a tool for endometriosis, infertility, or RPL diagnosis.

The Vaginal Microbiome: Patient- versus Physician-Collected Microbial Swab: A Pilot Study

The composition of the vaginal microbiota prior to an IVF/IVF-ICSI treatment can predict the chance of achieving a pregnancy. To improve clinical applicability and be more patient-friendly, the self-collection of vaginal samples would be preferable. However, the reliability of patient-collected samples compared to physician-collected samples remains unclear. This study compares microbiome outcomes from patient-collected versus physician-collected vaginal samples. This is a prospective pilot study consisting of two cohorts: Cohort I involved patient self-sampling of the vagina, followed by a physician-collected vaginal swab, while Cohort II involved the reversed order of collection. The interspace profiling (IS-Pro) technique was used to analyze the microbiota composition in all samples. From May 2021 to March 2022, a total of 444 samples were collected from n = 222 patients (aged 21-44 years), with Cohort I (n = 109) and Cohort II (n = 113). The vaginal microbiome composition of both cohorts was highly similar, regardless of the sampling order, with a mean cosine similarity of 0.93 (95% CI 0.91, 0.95) in Cohort I and 0.94 (95% CI 0.92, 0.96) in Cohort II. Furthermore, ANOVA analysis revealed no significant differences in bacterial species abundance between physician- and patient-collected samples, nor between first and second sample collections. The self-collection of vaginal samples can be considered comparable to physician-collected samples and indicates a more patient-friendly and convenient collection of the vaginal microbiome in an outpatient clinical setting.

Defining Vaginal Community Dynamics: daily microbiome transitions, the role of menstruation, bacteriophages, and bacterial genes

BACKGROUND

The composition of the vaginal microbiota during the menstrual cycle is dynamic, with some women remaining eu- or dysbiotic and others transitioning between these states. What defines these dynamics, and whether these differences are microbiome-intrinsic or mostly driven by the host is unknown. To address this, we characterized 49 healthy, young women by metagenomic sequencing of daily vaginal swabs during a menstrual cycle. We classified the dynamics of the vaginal microbiome and assessed the impact of host behavior as well as microbiome differences at the species, strain, gene, and phage levels.

RESULTS

Based on the daily shifts in community state types (CSTs) during a menstrual cycle, the vaginal microbiome was classified into four Vaginal Community Dynamics (VCDs) and reported in a classification tool, named VALODY: constant eubiotic, constant dysbiotic, menses-related, and unstable dysbiotic. The abundance of bacteria, phages, and bacterial gene content was compared between the four VCDs. Women with different VCDs showed significant differences in relative phage abundance and bacterial composition even when assigned to the same CST. Women with unstable VCDs had higher phage counts and were more likely dominated by L. iners. Their Gardnerella spp. strains were also more likely to harbor bacteriocin-coding genes.

CONCLUSIONS

The VCDs present a novel time series classification that highlights the complexity of varying degrees of vaginal dysbiosis. Knowing the differences in phage gene abundances and the genomic strains present allows a deeper understanding of the initiation and maintenance of permanent dysbiosis. Applying the VCDs to further characterize the different types of microbiome dynamics qualifies the investigation of disease and enables comparisons at individual and population levels. Based on our data, to be able to classify a dysbiotic sample into the accurate VCD, clinicians would need two to three mid-cycle samples and two samples during menses. In the future, it will be important to address whether transient VCDs pose a similar risk profile to persistent dysbiosis with similar clinical outcomes. This framework may aid interdisciplinary translational teams in deciphering the role of the vaginal microbiome in women's health and reproduction. Video Abstract.

Assessing vaginal microbiome through Vaginal Microecology Evaluation System as a predictor for in vitro fertilization outcomes: a retrospective study

Objective

This study aims to evaluate the effectiveness of the Vaginal Microecology Evaluation System (VMES) in assessing the dynamics of the vaginal microbiome (VM) throughout the process of in vitro fertilization and embryo transfer (IVF-ET). Furthermore, it seeks to explore the potential correlation between distinct types of VM ecology and the success rate of IVF-ET.

Methods

This study employed VMES to ascertain the composition of the VM. Data were collected from infertile women who underwent their initial IVF-ET treatment for tubal factor between January 2018 and December 2021. A retrospective analysis of pregnancy outcomes resulting from their fresh embryo transfer was conducted to determine the predictive significance of the vaginal microenvironment.

Results

We demonstrate that VMES is able to predict IVF-ET outcomes in patients diagnosed with Bacterial Vaginosis (BV). Notably, a discernible shift in the VM was observed in a decent subset of patients following Controlled Ovarian Stimulation (COS), though this phenomenon was not universal across all participants. Specifically, there was a noteworthy increase in the proportion of patients exhibiting BV and uncharacterized dysbiosis subsequent to COS. Furthermore, our investigation revealed a significant correlation between VM and both the live birth rate and early miscarriage rate. Employing a multivariable logistic regression model, we identified that VM status pre-COS, VM status post-COS, patient age, and the number of embryos transferred emerged as independent predictors of the live birth rate.

Conclusion

Our study suggests that, during IVF-ET treatment, the VMES can effectively detect changes in the VM, which are strongly correlated with the pregnancy outcome of IVF-ET procedures.

Pilot Study on Next-Generation Sequencing Analysis of Vaginal Microbiota in Clinically Infertile Patients Treated with Probiotics

Background: In this investigation, we aimed to understand the influence of oral probiotic supplementation on the vaginal microbiota of women preparing for assisted reproductive technology (ART) procedures. Given the importance of a healthy microbiome for reproductive success, this study sought to explore how probiotics might alter the bacterial composition in the vaginal environment. Methods: We recruited a cohort of 30 women, averaging 37 years of age (ranging from 31 to 43 years), who were scheduled to undergo ART. Using 16S ribosomal RNA (rRNA) sequencing, we meticulously analyzed the vaginal microbiota composition before and after the administration of oral probiotic supplements. Results: Our analysis identified 17 distinct microorganisms, including 8 species of Lactobacillus. Following probiotic supplementation, we observed subtle yet notable changes in the vaginal microbiota of some participants. Specifically, there was a decrease in Gardnerella abundance by approximately 20%, and increases in Lactobacillus and Bifidobacterium by 10% and 15%, respectively. Additionally, we noted a significant reduction in the Firmicutes/Bacteroidetes (F/B) ratio in the probiotic group, indicating potential shifts in the overall bacterial composition. Conclusions: These preliminary findings suggest that oral probiotic supplementation can induce significant changes in the vaginal microbiota of middle-aged women undergoing ART, potentially improving their overall bacterial profile. Future studies should consider a larger sample size and a narrower age range to validate these results. Investigating factors related to female hormone production could also provide deeper insights. Understanding the effects of probiotics on the vaginal microbiota in patients with ovarian aging may lead to personalized interventions and better reproductive outcomes.

Vaginal dysbiosis - the association with reproductive outcomes in IVF patients: a systematic review and meta-analysis

PURPOSE OF REVIEW

To examine impact of vaginal dysbiosis (VD), including bacterial vaginosis (BV) and aerobic vaginitis (AV) on reproductive outcomes of in vitro fertilization (IVF) patients.

RECENT FINDINGS

BV-bacteria (e.g. Gardnerella ) and AV-bacteria (e.g. Streptococci and Enterococci ) have been identified in the endometrium. However, there is inconclusive evidence whether IVF patients with VD have lower success rates.

SUMMARY

The present systematic review and meta-analysis of PubMed/Medline, until December 2023 included 25 studies, involving 6835 IVF patients. Overall VD was defined as an approximation of community state type IV, including BV and AV-type dysbiosis based on either molecular or microscopy methods. Outcomes were live birth rate (LBR), early pregnancy loss (EPL), clinical pregnancy rate (CPR), and biochemical pregnancy rate (BPR).Vaginal dysbiosis prevalence was 19% [1271/6835, 95% confidence interval (CI) 18-20%]. Six studies examined AV-type dysbiosis with a prevalence of 4% (26/628, 95% CI 3-6%). Vaginal dysbiosis correlates with a higher EPL [relative risk (RR) = 1.49, 95% CI 1.15-1.94] and lower CPR (RR = 0.82, 95% CI 0.70-0.95). No statistically significant impact of VD, BV, or AV was found on LBR and BPR.Thus, the association between VD and reproductive outcome remains puzzling as it is difficult to explain how VD impacts CPR and EPL but not LBR and BPR.

Vaginal microbiota are associated with in vitro fertilization during female infertility

The vaginal microbiome plays an essential role in the reproductive health of human females. As infertility increases worldwide, understanding the roles that the vaginal microbiome may have in infertility and in vitro fertilization (IVF) treatment outcomes is critical. To determine the vaginal microbiome composition of 1411 individuals (1255 undergoing embryo transplantation) and their associations with reproductive outcomes, clinical and biochemical features are measured, and vaginal samples are 16S rRNA sequenced. Our results suggest that both too high and too low abundance of Lactobacillus is not beneficial for pregnancy; a moderate abundance is more beneficial. A moderate abundance of Lactobacillus crispatus and Lactobacillus iners (~80%) (with a pregnancy rate of I-B: 54.35% and III-B: 57.73%) is found beneficial for pregnancy outcomes compared with a higher abundance (>90%) of Lactobacillus (I-A: 44.81% and III-A: 51.06%, respectively). The community state type (CST) IV-B (contains a high to moderate relative abundance of Gardnerella vaginalis) shows a similar pregnant ratio (48.09%) with I-A and III-A, and the pregnant women in this CST have a higher abundance of Lactobacillus species. Metagenome analysis of 71 samples shows that nonpregnant women are detected with more antibiotic-resistance genes, and Proteobacteria and Firmicutes are the main hosts. The inherent differences within and between women in different infertility groups suggest that vaginal microbes might be used to detect infertility and potentially improve IVF outcomes.

The microbiome in recurrent pregnancy loss - A scoping review

Recurrent pregnancy loss (RPL) is a troubling condition that affects couples worldwide. Despite extensive research efforts, many RPL cases remain unexplained, highlighting the need for novel approaches to unravel its underlying mechanisms. Recent advances in microbiome research have shed light on the potential role of the microbiome in reproductive health and outcomes. Based on a systematic literature research, this review aims to comprehensively explore the current understanding of the microbiome's involvement in RPL, focusing on the vaginal, endometrial, and gut microbiomes. Evidence from the available studies is examined to explain the relationship between the microbiome and RPL. Furthermore, we discuss the diagnostic potential of the microbiome, therapeutic interventions, and future directions in microbiome research for RPL. Understanding the complex interactions between the microbiome and reproductive health holds promise for developing targeted interventions to help patients today diagnosed as unexplained.

Understanding the Role of Female Genital Tract Microbiome in Recurrent Implantation Failure

The realization of the role of the microbiome of the female reproductive tract in health and disease has opened numerous possibilities for the scientific examination of the intertwining role between the human host and its microbiota. The imbalance in the composition of the microbial communities of the vagina and uterus is now recognized as a risk factor for many complications in pregnancy and according to the data from numerous studies, it is possible for this imbalance to play a crucial role in creating a hostile endometrial environment, and therefore, contributing to the etiology of recurrent implantation failure. Nevertheless, our current understanding of these complicated biological phenomena is far from complete, and in the future, there needs to be a systematic and thorough investigation of the diagnosis and therapy of this condition. This will enable scientists who engage in the field of assisted reproduction technologies to accurately identify and cure women in whom dysbiosis hinders the achievement of a healthy pregnancy.

Association between bacterial vaginosis, Chlamydia trachomatis infection and tubal factor infertility in Bukavu, Democratic Republic of Congo

BACKGROUND

Tubal factor infertility (TFI) is common in sub-Saharan Africa and often secondary to pelvic inflammatory disease (PID). Anaerobes associated with bacterial vaginosis (BV) are also found in PIDs widely dominated by Chlamydia trachomatis (C. trachomatis), whose role in TFI is better demonstrated than that of BV.

OBJECTIVES

To determine the prevalence of BV and C. trachomatis and to investigate the association between BV, C. trachomatis and TFI.

METHODS

We included 137 patients treated for infertility between January 2020 and November 2021. Cases were defined as women with infertility aged 18-45 years presenting with TFI (n = 52), and controls as infertile women in the same age groups without TFI (n = 85). Data on social habits, life style and infertility parameters were collected, and we performed screening for BV and C. trachomatis. Multiple regression was used to measure associations.

RESULTS

The prevalence of BV and C. trachomatis was 42.3% (58/137) and 23.4% (32/137), respectively. BV (61.5% vs 30.6%, p<0.001) and C. trachomatis (48.1 vs 8.2%, p<0.001) were more frequent in cases of TFI. BV and C. trachomatis increased the risk of TFI approximately 4-fold [aOR: 3.77 (1.61-8.83), p=0.002] and 14-fold [aOR: 13.77 (4.59-41.27), p<0.001], respectively.

CONCLUSION

BV and C. trachomatis infection are strongly associated with TFI in Bukavu. Prevention and screening should be implemented to reduce the risk of TFI.

Microbiome in Female Reproductive Health: Implications for Fertility and Assisted Reproductive Technologies

The microbiome plays a critical role in the process of conception and the outcomes of pregnancy. Disruptions in microbiome homeostasis in women of reproductive age can lead to various pregnancy complications, which significantly impact maternal and fetal health. Recent studies have associated the microbiome in the female reproductive tract (FRT) with assisted reproductive technology (ART) outcomes, and restoring microbiome balance has been shown to improve fertility in infertile couples. This review provides an overview of the role of the microbiome in female reproductive health, including its implications for pregnancy outcomes and ARTs. Additionally, recent advances in the use of microbial biomarkers as indicators of pregnancy disorders are summarized. A comprehensive understanding of the characteristics of the microbiome before and during pregnancy and its impact on reproductive health will greatly promote maternal and fetal health. Such knowledge can also contribute to the development of ARTs and microbiome-based interventions.

Impact of vaginal microecological differences on pregnancy outcomes and endometrial microbiota in frozen embryo transfer cycles

PURPOSE

This prospective study investigates the correlation between vaginal microecology and pregnancy outcomes and explores their impact on endometrial microbiota composition during frozen embryo transfer (FET) cycles. Additionally, the impact of transvaginal Lactobacillus supplementation on reproductive outcomes in patients with previous failed cycles was assessed.

METHODS

A total of 379 patients undergoing FET at a reproductive medicine center were categorized into clinical pregnancy (CP), miscarriage (MISC), and non-pregnant (NP) groups. Vaginal specimens were collected for microecological evaluation prior to embryo transfer. Endometrial microbiota samples were obtained during embryo transfer for 16S rRNA gene sequencing analysis to assess endometrial microbiota composition. Vaginal microecological indicators, including pH, Lactobacillus dominance, and leukocyte esterase activity, were measured. Transvaginal Lactobacillus supplementation was investigated in 60 patients with previous failed cycles.

RESULTS

Vaginal microecology significantly correlated with pregnancy outcomes, with normal microecology associated with a higher clinical pregnancy rate. Vaginal pH and leukocyte esterase activity were significantly associated with clinical pregnancy. Furthermore, vaginal microecological differences significantly impacted endometrial microbiota composition. However, no significant differences were observed in endometrial microbiota composition among the CP, MISC, and NP groups. Notably, transvaginal Lactobacillus supplementation increased the clinical pregnancy rate without affecting the miscarriage rate.

CONCLUSION

This study highlights that normal vaginal microecology, characterized by lower pH and leukocyte esterase negativity, is associated with a higher likelihood of clinical pregnancy following FET. Importantly, vaginal microecological differences influence endometrial microbiota composition. Moreover, transvaginal Lactobacillus supplementation appears promising in improving clinical pregnancy rates in patients with previous failed cycles. These findings contribute to a better understanding of the interplay between vaginal and endometrial microbiota and offer potential interventions to enhance reproductive success in assisted reproductive technologies.

Bacterial vaginosis in a subfertile population undergoing fertility treatments: a prospective cohort study

PURPOSE

This study investigates the role of bacterial vaginosis (BV) on pregnancy rates during various fertility treatments. BV is known to influence several obstetric outcomes, such as preterm delivery and endometritis. Only few studies investigated the effect of BV in subfertile women, and studies found a negative effect on fecundity especially in the in vitro fertilisation population.

METHODS

Observational prospective study, 76 couples attending a fertility clinic in the Netherlands between July 2019 and June 2022, undergoing a total of 133 attempts of intra uterine insemination, in vitro fertilization or intra cytoplasmatic sperm injection. Vaginal samples taken at oocyte retrieval or insemination were analysed on qPCR BV and 16S rRNA gene microbiota analysis of V1-V2 region. Logistic regression with a Generalized Estimated Equations analysis was used to account for multiple observations per couples.

RESULTS

A total of 26% of the 133 samples tested positive for BV. No significant differences were observed in ongoing pregnancy or live birth rates based on BV status (OR 0.50 (0.16-1.59), aOR 0.32 (0.09-1.23)) or microbiome community state type. There was a tendency of more miscarriages based on positive BV status (OR 4.22 (1.10-16.21), aOR 4.28 (0.65-28.11)) or community state type group III and IV. On baseline qPCR positive participants had significantly higher body mass index and smoked more often. Odds ratios were adjusted for smoking status, body mass index, and socioeconomic status.

CONCLUSION

Bacterial vaginosis does not significantly impact ongoing pregnancy rates but could affect miscarriage rates.

Clinical Relevance of Vaginal and Endometrial Microbiome Investigation in Women with Repeated Implantation Failure and Recurrent Pregnancy Loss

Recent studies have investigated if and how the vaginal and endometrial microbiome might affect endometrial receptivity and reproductive health. Although there is no consensus on the existence of a core uterine microbiome yet, evidence shows that the dominance of Lactobacillus spp. in the female reproductive tract is generally associated with eubiosis and improved chances of successful implantation and an ongoing pregnancy. Conversely, vaginal and endometrial dysbiosis can cause local inflammation and an increase of pro-inflammatory cytokines, compromising the integrity and receptivity of the endometrial mucosa and potentially hampering successful embryonic implantation. This review provides a critical appraisal of the influence of the vaginal and endometrial microbiome as parts of the female reproductive tract on fertility outcomes, focusing on repeated implantation failure (RIF) and recurrent pregnancy loss (RPL). It seems that RIF as well as RPL are both associated with an increase in microbiome diversity and a loss of Lactobacillus dominance in the lower female reproductive system.

Detection and evaluation of different morphological forms of Mycoplasma hominis in human semen

Recently discovered microcolonial forms of Mycoplasma hominis ( M. hominis ) and their impact on human spermatogenesis are studied. The spermatozoa of 125 fertile men (sperm donors; from Reprobank [Reproductive Tissue Bank, Moscow, Russia]) and of 93 patients with fertility problems (from the Federal State Budgetary Institution "Research Centre for Medical Genetics [RCMG]", Moscow, Russia) were used. Classical colonies of M. hominis and microcolonies were detected by molecular biological methods, culture of bacteria, and transmission electron microscopy. The unique structure of microcolonial cells, in which the cytoplasmic cylinder is surrounded by concentric electron-dense and electron-light layers with a periodicity of 12-14 nm, and the ability of microcolonial cells to attach to spermatozoa are shown. In patients with lower sperm quality, microcolonies of M. hominis were detected 2.5 times more frequently than classical colonies. The detection of microcolonies in the ejaculate and the frequent isolation of microcolonies from sperm samples of patients with fertility problems suggest that microcolonial cells may be one cause of infertility.

Longitudinal analysis of vaginal microbiota during IVF fresh embryo transfer and in early pregnancy

IMPORTANCE

Infertility is a global public health issue which leads many couples to seek fertility treatments, of which in vitro fertilization (IVF) is considered to be the most effective. Still, only about one-third of the women achieve live birth after the first IVF embryo transfer (IVF-ET). Factors affecting embryo implantation are poorly known, but the female reproductive tract microbiota may play a key role. Our study confirms the beneficial role of vaginal lactobacilli, especially Lactobacillus crispatus, in the probability of achieving clinical pregnancy and live birth following IVF-ET. Our findings regarding the intra-individual shift of vaginal microbiota between non-pregnancy and pregnancy states are novel and provide new information about the dynamics of microbiota in the early steps of human reproduction. These findings may help clinicians in their attempts to optimize the conditions for ET by microbiota screening or modulation and timing the ET when the microbiota is the most favorable.

A Novel Approach to Predicting Early Pregnancy Outcomes Dynamically in a Prospective Cohort Using Repeated Ultrasound and Serum Biomarkers

This study aimed to develop a dynamic model for predicting outcome during the first trimester of pregnancy using baseline demographic data and serially collected blood samples and transvaginal sonographies. A prospective cohort of 203 unselected women with an assumed healthy pregnancy of < 8 weeks' gestation was followed fortnightly from 4-14 weeks' gestation until either miscarriage or confirmed first trimester viability. The main outcome was development of a model to predict outcome from gestational age-dependent hazard ratios using both baseline and updated serial data from each visit. Secondary outcomes were descriptions of risk factors for miscarriage. The results showed that 18% of the women experienced miscarriages. A fetal heart rate detected before 8 weeks' gestation indicated a 90% (95% CI 85-95%) chance of subsequent delivery. Maternal age (≥ 35 years), insufficient crown-rump-length (CRL) and mean gestational sac diameter (MSD) development, and presence of bleeding increased the risk of miscarriage. Serum biomarkers, including hCG, progesterone, and estradiol, were found to impact the risk of miscarriage with estradiol as the most important. The best model to predict miscarriage was a combination of maternal age, vaginal bleeding, CRL, and hCG. The second-best model was the sonography-absent model of maternal age, bleeding, hCG, and estradiol. This study suggests that combining maternal age, and evolving data from hCG, estradiol, CRL, and bleeding could be used to predict fetal outcome during the first trimester of pregnancy.Trial registration ClinicalTrials.gov identifier: NCT02761772.

The effect of normalizing vaginal microbiome using Lactovag in improving pregnancy outcomes in frozen embryo transfer cycles: a randomized clinical trial

INTRODUCTION

Successful frozen-thawed embryo transfer (FTET) depends on multiple factors among which the woman's vaginal microbiota has recently been considered important. Using probiotic products, such as Lactovag in infertile women, the vaginal microbiome can become close to the healthy status.

OBJECTIVES

The aim of this study was to evaluate the effect of Lactovag on normalizing vaginal microbiome, as well as its role in improving pregnancy outcomes in FTET cycles.

PATIENTS AND METHODS

This randomized blinded clinical trial was conducted on 103 patients undergoing Assisted Reproductive Technology (ART) treatment at a tertiary university-based hospital between January and August of 2019. In the experiment group, the vaginal suppository Lactavag was prescribed, whereas in the control group, patients did not receive any microbiome supplements. Then, the pregnancy rate was compared in the two groups.

RESULTS

There were no significant differences in baseline characteristics between the two study groups (p > 0.05). Positive B hCG was present in 28% (n = 26) of women, clinical pregnancy was achieved in 23.4% (n = 22) of them and fetal heart rate was detected in 21.3% (n = 20). These proportions were higher in the Lactovag group, although these differences were not significant (p > 0.05). Results showed that although transferring fetuses with grade A increased the odds of pregnancy with 1.53 (p = 0.001) folds, this ratio would be improved using Lactovag;1.68 (P value = 0.008).

CONCLUSIONS

It seems that the vaginal microbiota critically interplays with women's health and reproduction. A probiotic agent such as Lactovag can be useful in normalizing this environment and improving pregnancy outcomes in infertile women.

Menstrual Tampons Are Reliable and Acceptable Tools to Self-Collect Vaginal Microbiome Samples

Many women report embarrassment as the cause for their avoidance of routine gynaecological screening appointments. Methods of self-collection of bio samples would perhaps encourage women to participate in routine screening programs. The vaginal microbiome plays a key role in women's health and reproductive function. Microbial disturbances can result in the loss of lactobacillus dominance, also known as dysbiosis, associated with an increased risk of contracting sexually transmitted infections (STIs), pregnancy complications and infertility. Our primary aim was to determine if vaginal microbiome screening results are comparable between two methods for self-collected sample acquisition: tampons and lower vaginal swabs (LVSs). Secondary aims included the assessment of the effect of pre-analytic storage on the data (to streamline processing), the prevalence of dysbiosis and the acceptability of the tampons to the participants. Statistical analysis revealed no significant difference in the microbiome data, from tampons versus LVSs or fresh versus frozen samples. The prevalence of dysbiosis in this population of healthy volunteers was 42.9%. The questionnaire data revealed that 52.4% of volunteers use tampons every period, and the majority of volunteers rated the tampons as 5 on a 1-5 Likert scale regarding their perceived comfort using tampons. All (100%) of volunteers were happy to provide a tampon as a sample for testing. The findings from this study show that tampons and LVSs were comparable when analysing the vaginal microbiome, with potential superiority of the tampon with regard to patient acceptability. Self-collection of vaginal secretions for gynaecological screening using tampons warrants further research as this could change the screening landscape, ensuring wider participation and increasing efficacy.

New Insights into Photobiomodulation of the Vaginal Microbiome-A Critical Review

The development of new technologies such as sequencing has greatly enhanced our understanding of the human microbiome. The interactions between the human microbiome and the development of several diseases have been the subject of recent research. In-depth knowledge about the vaginal microbiome (VMB) has shown that dysbiosis is closely related to the development of gynecologic and obstetric disorders. To date, the progress in treating or modulating the VMB has lagged far behind research efforts. Photobiomodulation (PBM) uses low levels of light, usually red or near-infrared, to treat a diversity of conditions. Several studies have demonstrated that PBM can control the microbiome and improve the activity of the immune system. In recent years, increasing attention has been paid to the microbiome, mostly to the gut microbiome and its connections with many diseases, such as metabolic disorders, obesity, cardiovascular disorders, autoimmunity, and neurological disorders. The applicability of PBM therapeutics to treat gut dysbiosis has been studied, with promising results. The possible cellular and molecular effects of PBM on the vaginal microbiome constitute a theoretical and promising field that is starting to take its first steps. In this review, we will discuss the potential mechanisms and effects of photobiomodulation in the VMB.

Vaginal microbiome in obesity and its impact on reproduction

A number of reproductive outcomes have been increasingly found to be affected by the vaginal microbiota. Obesity has become a global epidemic, affecting increasing numbers of reproductive-age women, and has been shown to be a risk factor for a number of adverse female health outcomes. A healthy vaginal microbiome is characterized by Lactobacillus-dominance, in particular Lactobacillus crispatus; obesity has been found to be associated with higher diversity and a lower likelihood of Lactobacillus-dominance. In this review, we summarize the evidence on the vaginal microbiome in obese women and the impact on reproductive outcomes such as conception rates, early pregnancy, and preterm birth. We further explore the mechanisms by which obesity may result in an altered microbial composition and highlight future avenues for therapeutic targeting of the vaginal microbiota.

Intrauterine colonization with Gardnerella vaginalis and Mobiluncus mulieris induces maternal inflammation but not preterm birth in a mouse model

PROBLEM

Preterm birth (PTB) remains a leading cause of childhood mortality. Recent studies demonstrate that the risk of spontaneous PTB (sPTB) is increased in individuals with Lactobacillus-deficient vaginal microbial communities. One proposed mechanism is that vaginal microbes ascend through the cervix, colonize the uterus, and activate inflammatory pathways leading to sPTB. This study assessed whether intrauterine colonization with either Gardnerella vaginalis and Mobiluncus mulieris alone is sufficient to induce maternal-fetal inflammation and induce sPTB.

METHOD OF STUDY

C56/B6J mice, on embryonic day 15, received intrauterine inoculation of saline or 108 colony-forming units of G. vaginalis (n = 30), M. mulieris (n = 17), or Lactobacillus crispatus (n = 16). Dams were either monitored for maternal morbidity and sPTB or sacrificed 6 h post-infusion for analysis of bacterial growth and cytokine/chemokine expression in maternal and fetal tissues.

RESULTS

Six hours following intrauterine inoculation with G. vaginalis, M. mulieris, or L. crispatus, live bacteria were observed in both blood and amniotic fluid, and a potent immune response was identified in the uterus and maternal serum. In contrast, only a limited immune response was identified in the amniotic fluid and the fetus after intrauterine inoculation. High bacterial load (108 CFU/animal) of G. vaginalis was associated with maternal morbidity and mortality but not sPTB. Intrauterine infusion with L. crispatus or M. mulieris at 108 CFU/animal did not induce sPTB, alter pup viability, litter size, or maternal mortality.

CONCLUSIONS

Despite inducing an immune response, intrauterine infusion of live G. vaginalis or M. mulieris is not sufficient to induce sPTB in our mouse model. These results suggest that ascension of common vaginal microbes into the uterine cavity alone is not causative for sPTB.

Effect of vaginal microbiota on pregnancy outcomes of women from Northern China who conceived after IVF

Objective

This study aimed to investigate the correlation between vaginal microbiota and pregnancy outcomes of women who achieved pregnancy via in vitro fertilization (IVF) in Northern China, and to determine a biomarker for evaluation of the risk of preterm births in these women.

Methods

In total, 19 women from Northern China women who conceived after IVF and 6 women who conceived naturally were recruited in this study. The vaginal samples of the healthy participants were collected throughout pregnancy, that is, during the first, second, and third trimesters. The V3-V4 region of 16S rRNA was used to analyze the vaginal microbiome, and the bioinformatic analysis was performed using QIIME Alpha and Beta diversity analysis.

Results

Either IVF group or Natural conception group, bacterial community diversities and total species number of vagnal samples from who delivered at term were significantly higher than those who delivered before term. Low abundance of vaginal bacteria indicates an increased risk of preterm delivery. Further, more abundant vaginal bacteria was found in first trimesters instead of the next two trimesters. Vignal samples collected during first trimester showed richer differences and more predictive value for pregnancy outcoes. In addition, the diversity of the vaginal bacterial community decreased as the gestational age increased, in all samples. Alloscardovia was only found in participants who conceived after IVF, and the percentage of Alloscardovia in viginal samples of normal delivery group is much higher than the samples from preterm delivery group.Vobrio specifically colonized in vagina of pregnant woman in AFT group (those who conceived after IVF (A), first trimester (F), and delivered at term (T)) and Sporosarcina was detected only in women with AFT and AST (those who conceived after IVF (A), second trimester (S), and delivered at term (T)). These data indicates that Alloscardovia, Vobrio and Sporosarcina have great potential in predicting pregnancy outcomes who pregnanted by vitro fertilization.

Conclusions

Vaginal microbiota were more stable in women who conceived naturally and those who carried pregnancy to term. Oceanobacillus might act as a positive biomarker, whereas Sulfurospirillum and Propionispira may act as negative biomarkers for the risk of preterm birth.

An Overview of the Microbiota of the Human Urinary Tract in Health and Disease: Current Issues and Perspectives

This article is intended to deepen our knowledge to date regarding the functions of the resident microbiota/microbiome in the urinary system for human health and disease. First, we sought to report the general characteristics (composition and stability) of the normal urinary system microbiota in the different anatomical sites in relation to some factors such as the effect of age, gender and diet, analyzing in detail the functions and the composition of the microbiota in the light of current knowledge. Several pieces of evidence suggest the importance of preserving the micro-ecosystem of the urinary system, and in some cases their relationship with diseases is important for maintaining human health is well understood. The female and male reproductive microbiota have mainly been studied over the past decade. In the past, the arrest was thought to have taken place in a sterile environment. Microorganisms of the microbiota form biofilms, three-dimensional structures, that differ in the reproductive organs and interact with both gametes and the embryo as well as with maternal tissues. These biofilms from the reproductive system also interact with others, such as that of the gastrointestinal tract. Reduction in its diversity intestinal microbiota can disrupt estrogen metabolism and affect the reproductive microbiota. It is therefore understood that its quantitative and qualitative identification is important for microbiota, but also the study of the structures formed by the microorganisms. A dysbiosis with local or systemic causes can lead to serious diseases. The role of probiotics in maintaining microbial population harmony (eubiosis) and preventing certain pathologies of the urinary and reproductive system was also investigated. A negative variation in the qualitative and quantitative composition of certain strains of microorganisms (dysbiosis) due to local or systemic causes can even lead to serious diseases. The role of probiotics in maintaining the healthy balance of microorganism populations (eubiosis), and thus in the prevention of certain pathologies of the urinary and reproductive system, has also been studied.

Cycle Biodynamics of Women's Microbiome in the Urinary and Reproductive Systems

The genitourinary microbiome plays a crucial role in the establishment and maintenance of urinary and reproductive health in women throughout their lives. Particularly during the reproductive stage, resident microorganisms contribute to implantation and protect against perinatal complications, including preterm birth, stillbirth, and low birth weight, while also serving as the first line of defense against pathogens that can cause infections, such as urinary tract infections and bacterial vaginosis. This review aimed to elucidate the relationship between a healthy microbiome environment and women's overall health. We examine the variability and dynamics of the microbiome during different developmental stages, ranging from the prepubertal to the postmenopausal stage. Furthermore, we explore the significance of a healthy microbiota in successful implantation and pregnancy development and investigate potential differences between women experiencing infertility. In addition, we analyze the local and systemic inflammatory responses associated with the establishment of a dysbiotic state and compare it to a condition where a healthy microbiome was established. Lastly, we present the most recent evidence regarding preventive measures, such as dietary interventions and the use of probiotics to promote and maintain a healthy microbiome, thereby ensuring comprehensive women's health. By highlighting the importance of the genitourinary microbiome in reproductive health, this review aimed to enhance this microbiome's visibility and significance in the field.

The Female Reproductive Tract Microbiota: Friends and Foe

We do not seem to be the only owner of our body; it houses a large population of microorganisms. Through countless years of coevolution, microbes and hosts have developed complex relationships. In the past few years, the impact of microbial communities on their host has received significant attention. Advanced molecular sequencing techniques have revealed a remarkable diversity of the organ-specific microbiota populations, including in the reproductive tract. Currently, the goal of researchers has shifted to generate and perceive the molecular data of those hidden travelers of our body and harness them for the betterment of human health. Recently, microbial communities of the lower and upper reproductive tract and their correlation with the implication in reproductive health and disease have been extensively studied. Many intrinsic and extrinsic factors influences the female reproductive tract microbiota (FRTM) that directly affects the reproductive health. It is now believed that FRTM dominated by Lactobacilli may play an essential role in obstetric health beyond the woman's intimate comfort and well-being. Women with altered microbiota may face numerous health-related issues. Altered microbiota can be manipulated and restored to their original shape to re-establish normal reproductive health. The aim of the present review is to summarize the FRTM functional aspects that influence reproductive health.

The Impact of the Female Genital Microbiota on the Outcome of Assisted Reproduction Treatments

The vaginal microbiota plays a critical role in the health of the female genital tract, and its composition contributes to gynecological disorders and infertility. Lactobacilli are the dominant species in the female genital tract: their production of lactic acid, hydrogen peroxide, and bacteriocins prevents the invasion and growth of pathogenic microorganisms. Several factors such as hormonal changes, age of reproduction, sexual practices, menstrual cycle, pregnancy, and antimicrobial drugs use can cause imbalance and dysbiosis of the vaginal microbiota. This review aims to highlight the impact of the vaginal microbiota in Assisted Reproductive Technology techniques (ART) and it examines the factors that influence the vaginal microbiota, the consequences of dysbiosis, and potential interventions to restore a healthy female genital tract.

Impact of a Lactobacillus dominant cervical microbiome, based on 16S-FAST profiling, on the reproductive outcomes of IVF patients

Objective

This study assessed the impact of the cervical microbiome on reproductive outcomes in frozen embryo transfer (FET) patients.

Study design

This cross-sectional study included 120 women (aged 20-40 years) undergoing FET. A cervical sample obtained before embryo transfer was analyzed using 16S full-length assembly sequencing technology (16S-FAST), which detects full length 16S rDNA.

Results

We found that >48% of the identified Lactobacillus species were novel. The cervical microbiome was clustered into three cervical microbiome types (CMT): CMT1, dominated by L. crispatus; CMT2, dominated by L. iners; and CMT3, dominated by other bacteria. CMT1 had a significantly higher biochemical pregnancy rate (P=0.008) and clinical pregnancy rate (P=0.006) than CMT2 and CMT3. Logistic analysis showed that compared to CMT1, CMT2 and CMT3 were independent risk factors for biochemical pregnancy failure (odds ratio [OR]: 6.315, 95% confidence interval [CI]: 2.047-19.476, P=0.001; OR: 3.635, 95% CI: 1.084-12.189, P=0.037) and clinical pregnancy failure (OR: 4.883, 95% CI: 1.847-12.908, P=0.001; OR: 3.478, 95% CI: 1.221-9.911, P=0.020). A L. crispatus-dominated group as a diagnostic indicator of biochemical and clinical pregnancy positive had area under the curve (AUC) values of 0.651(P=0.008) and 0.645(P=0.007), respectively. Combining the cervical microbiome with embryonic stage optimized the diagnostic performance for biochemical and clinical pregnancy failure with AUC values of 0.743(P<0.001) and 0.702(P<0.001), respectively. Additionally, relative abundance of L. crispatus predicted biochemical pregnancy positive with AUC values of 0.679(P=0.002) and clinical pregnancy positive with AUC values of 0.659(P=0.003).

Conclusion

Cervical microbiome profiling using 16S-FAST enables stratification of the chance of becoming pregnant prior to FET. Knowledge of the cervical microbiota may enable couples to make more balanced decisions regarding the timing and continuation of FET treatment cycles.

The Role of Hydrogen-Peroxide (H2O2) Produced by Vaginal Microbiota in Female Reproductive Health

Female reproductive health is strongly associated with healthy vaginal microbiota, which is thought to be ensured by the dominance of certain Lactobacillus species. Lactobacilli control the vaginal microenvironment through several factors and mechanisms. One of them is their ability to produce hydrogen peroxide (H₂O₂). The role of Lactobacillus-derived H₂O₂ in the vaginal microbial community has been intensively investigated in several studies with many designs. However, results and data are controversial and challenging to interpret in vivo. Defining the underlying mechanisms responsible for a physiological vaginal ecosystem is crucial since it could directly affect probiotic treatment attempts. This review aims to summarize current knowledge on the topic, focusing on probiotic treatment possibilities.

Fabrication and characterization of bioprints with Lactobacillus crispatus for vaginal application

Bacterial vaginosis (BV) is characterized by low levels of lactobacilli and overgrowth of potential pathogens in the female genital tract. Current antibiotic treatments often fail to treat BV in a sustained manner, and > 50% of women experience recurrence within 6 months post-treatment. Recently, lactobacilli have shown promise for acting as probiotics by offering health benefits in BV. However, as with other active agents, probiotics often require intensive administration schedules incurring difficult user adherence. Three-dimensional (3D)-bioprinting enables fabrication of well-defined architectures with tunable release of active agents, including live mammalian cells, offering the potential for long-acting probiotic delivery. One promising bioink, gelatin alginate has been previously shown to provide structural stability, host compatibility, viable probiotic incorporation, and cellular nutrient diffusion. This study formulates and characterizes 3D-bioprinted Lactobacillus crispatus-containing gelatin alginate scaffolds for gynecologic applications. Different weight to volume (w/v) ratios of gelatin alginate were bioprinted to determine formulations with highest printing resolution, and different crosslinking reagents were evaluated for effect on scaffold integrity via mass loss and swelling measurements. Post-print viability, sustained-release, and vaginal keratinocyte cytotoxicity assays were conducted. A 10:2 (w/v) gelatin alginate formulation was selected based on line continuity and resolution, while degradation and swelling experiments demonstrated greatest structural stability with dual genipin and calcium crosslinking, showing minimal mass loss and swelling over 28 days. 3D-bioprinted L. crispatus-containing scaffolds demonstrated sustained release and proliferation of live bacteria over 28 days, without impacting viability of vaginal epithelial cells. This study provides in vitro evidence for 3D-bioprinted scaffolds as a novel strategy to sustain probiotic delivery with the ultimate goal of restoring vaginal lactobacilli following microbiological disturbances.

Advances in Research on the Relationship between Vaginal Microbiota and Adverse Pregnancy Outcomes and Gynecological Diseases

The human microbiota inhabiting different parts of the body has been shown to have a significant impact on human health, with the gut microbiota being the most extensively studied in relation to disease. However, the vaginal microbiota is also an essential commensal microbiota in the female body that plays a crucial role in female health. Despite receiving less attention than gut microbiota, its importance in regulating reproductive immunity and its complex dynamic properties have been increasingly recognized in recent years. Advances in research on the relationship between vaginal microbiota and pregnancy outcomes & gynecological diseases in women have shed light on the importance of maintaining a healthy vaginal microbiota. In this review, we aim to compile recent developments in the study of the vaginal microbial ecosystem and its role in female health and reproductive outcomes. We provide a comprehensive account of the normal vaginal microbiota, the association between the vaginal microbiota and pregnancy outcomes, and the impact of the vaginal microbiota on gynecological diseases in women. By reviewing recent research, we hope to contribute to the advancement of academic medicine's understanding of the vaginal microbiota's importance in female health. We also aim to raise awareness among healthcare professionals and the general public of the significance of maintaining a healthy vaginal microbiota for better reproductive health and the prevention of gynecological diseases.

Distinct cervical tissue-adherent and luminal microbiome communities correlate with mucosal host gene expression and protein levels in Kenyan sex workers

BACKGROUND

The majority of studies characterizing female genital tract microbiota have focused on luminal organisms, while the presence and impact of tissue-adherent ectocervical microbiota remain incompletely understood. Studies of luminal and tissue-associated bacteria in the gastrointestinal tract suggest that these communities may have distinct roles in health and disease. Here, we performed a multi-omics characterization of paired luminal and tissue samples collected from a cohort of Kenyan female sex workers.

RESULTS

We identified a tissue-adherent bacterial microbiome, with a higher alpha diversity than the luminal microbiome, in which dominant genera overall included Gardnerella and Lactobacillus, followed by Prevotella, Atopobium, and Sneathia. About half of the L. iners-dominated luminal samples had a corresponding Gardnerella-dominated tissue microbiome. Broadly, the tissue-adherent microbiome was associated with fewer differentially expressed host genes than the luminal microbiome. Gene set enrichment analysis revealed that L. crispatus-dominated tissue-adherent communities were associated with protein translation and antimicrobial activity, whereas a highly diverse microbial community was associated with epithelial remodeling and pro-inflammatory pathways. Tissue-adherent communities dominated by L. iners and Gardnerella were associated with lower host transcriptional activity. Tissue-adherent microbiomes dominated by Lactobacillus and Gardnerella correlated with host protein profiles associated with epithelial barrier stability, although with a more pro-inflammatory profile for the Gardnerella-dominated microbiome group. Tissue samples with a highly diverse composition had a protein profile representing cell proliferation and pro-inflammatory activity.

CONCLUSION

We identified ectocervical tissue-adherent bacterial communities in all study participants of a female sex worker cohort. These communities were distinct from cervicovaginal luminal microbiota in a significant proportion of individuals. We further revealed that bacterial communities at both sites correlated with distinct host gene expression and protein levels. The tissue-adherent bacterial community could possibly act as a reservoir that seed the lumen with less optimal, non-Lactobacillus, bacteria. Video Abstract.

Characterization of the Endometrial Microbiome in Patients with Recurrent Implantation Failure

An abnormal endometrial microbiota has been associated with implantation failure; therefore, it may be important to evaluate it in order to improve reproductive outcomes in infertile patients. The main objective of our study was to compare the endometrial microbiome of patients with recurrent implantation failure (RIF) and control patients undergoing assisted reproduction treatment (ART). A prospective cohort study including forty-five patients with their own or donated gametes. The endometrial microbiome was analysed by massive sequencing of the bacterial 16S rRNA gene. Different bacterial communities were detected in RIF and control patients. Lactobacillus stands out as the most frequent genus, with 92.27% in RIF patients and 97.96% in control patients, and significant differences were reported between the two groups (p = 0.002). No significant differences were found regarding alpha diversity index. In beta diversity analysis, a significant trend was observed in the separation of the bacterial community between established groups (p < 0.07). Relative abundance analysis identified genera Prevotella (p < 0.001), Streptococcus (p < 0.001), Bifidobacterium (p = 0.002), Lactobacillus (p = 0.002) and Dialister (p = 0.003). Our results demonstrated the existence of an endometrial microbiota characteristic of RIF patients and showed that there might be a relationship between population of the endometrial microbiome and embryo implantation failure, providing us the possibility to improve clinical results in this patients.

A pilot study using unique targeted testing of the urogenital microbiome has potential as a predictive test during IVF for implantation outcome

PURPOSE

This pilot study aimed to develop a methodology characterising the urogenital microbiome as a predictive test in the IVF workup.

METHODS

Using unique custom qPCRs, we tested for the presence of specific microbial species from vaginal samples and First Catch Urines from the male. The test panel included a range of potential urogenital pathogens, STIs, 'favourable bacteria' (Lactobacillus spp.) and 'unfavourable bacteria' (anaerobes) reported to influence implantation rates. We tested couples attending Fertility Associates, Christchurch, New Zealand for their first round of IVF.

RESULTS

We found that some microbial species affected implantation. The qPCR result was interpreted qualitatively using the Z proportionality test. Samples from women at the time of Embryo Transfer who did not achieve implantation had significantly higher percent of samples that were positive for Prevotella bivia and Staphylococcus aureus compared to women who did achieve implantation.

DISCUSSION

The results provide evidence that most other microbial species chosen for testing had little functional effect on implantation rates. The addition of further microbial targets (yet to be determined) could be combined in this predictive test for vaginal preparedness on the day of embryo transfer. This methodology has a substantial advantage of being affordable and easily performed in any routine molecular laboratory. This methodology is most suitable as a foundation on which to develop a timely test of microbiome profiling. Using the indicators detected to have a significant influence, these results can be extrapolated.

CONCLUSION

Using a rapid antigen test, a woman can self-sample prior to embryo transfer and obtain an indication of microbial species present which could influence implantation outcome.

Correlations of joint detection of 22 vaginal microbes with routine examination results of vaginal secretions and assisted reproductive outcomes

The correlations of joint detection of 22 vaginal microbes with routine examination results of vaginal secretions and assisted reproductive outcomes were investigated. There were 37 samples with abnormal vaginal microecology in 107 vaginal secretion samples. The top 5 detection rates of microorganisms were Ureaplasma urealyticum (73.83%), Prevotella sp. (70.09%), Gardnerella vaginalis (53.27%), L. crispatus (52.34%) and L. inerts (51.40%). When the levels of Bacillus and hydrogen peroxide in vaginal secretions decreased or pH increased, the abnormal rates of vaginal microecology increased significantly (P < 0.01). The clinical pregnancy rate (53.66%, 22/41) in the women with normal vaginal microecology was higher than that (37.5%, 9/24) with abnormal vaginal microecology. In conclusions, the joint detection of 22 vaginal microbes can quickly and effectively determine whether the vaginal microecology is normal or not. The evaluation of vaginal microecology may be valuable in predicting the assisted reproductive outcomes of infertile women.

The endometrial microbiota of women with or without a live birth within 12 months after a first failed IVF/ICSI cycle

The endometrial microbiota composition may be associated with implantation success. However, a 'core' composition has not yet been defined. This exploratory study analysed the endometrial microbiota by 16S rRNA sequencing (V1-V2 region) of 141 infertile women whose first IVF/ICSI cycle failed and compared the microbiota profiles of women with and without a live birth within 12 months of follow-up, and by infertility cause and type. Lactobacillus was the most abundant genus in the majority of samples. Women with a live birth compared to those without had significantly higher Lactobacillus crispatus relative abundance (RA) (p = 0.029), and a smaller proportion of them had ≤ 10% L. crispatus RA (42.1% and 70.4%, respectively; p = 0.015). A smaller proportion of women in the male factor infertility group had ≤ 10% L. crispatus RA compared to women in the unexplained and other infertility causes groups combined (p = 0.030). Women with primary infertility compared to secondary infertility had significantly higher L. crispatus RA (p = 0.004); lower proportions of them had ≤ 10% L. crispatus RA (p = 0.009) and > 10% Gardnerella vaginalis RA (p = 0.019). In conclusion, IVF/ICSI success may be associated with L. crispatus RA and secondary infertility with endometrial dysbiosis, more often than primary infertility. These hypotheses should be tested in rigorous well-powered longitudinal studies.

Female reproductive tract microbiome and early miscarriages

Miscarriage is one of the main causes of reproductive loss, which can lead to a number of physical and psychological complications and other long-term consequences. However, the role of vaginal and uterine microbiome in such complications is poorly understood. To review the published data on the function of the female reproductive tract microbiome in the pathogenesis of early miscarriages. The articles published over the past 20 years and deposited in PubMed, Google Academy, Scopus, Elibrary, ResearchGate, and EBSCO databases were analyzed. The review presents new data on the impact of the vaginal and uterine microbiome on the local immunity, including defense against sexually transmitted infections, and its association with other factors of miscarriages. The studies on the microbiome of non-pregnant women with recurrent miscarriages in the anamnesis, patients undergoing IVF, and pregnant women with miscarriages, as well as new directions in the microbiome research are discussed. The majority of studies have demonstrated that the dominant species of the vaginal and uterine microbiome in patients with early miscarriages are non-Lactobacillus bacteria. As many of these bacteria have not previously been detected by cultural studies and their role in obstetric complications is not well defined, further research on the female reproductive tract microbiome, including the microbiome of the cervix uteri, is needed to develop new approaches for the prognosis and prevention of miscarriages.

The Vaginal Microbiome in Health and Disease-What Role Do Common Intimate Hygiene Practices Play?

The vaginal microbiome is a dynamic, sensitive microenvironment. The hallmark of a 'healthy' vaginal microbiome is currently believed to be one dominated by Lactobacillus spp., which acidifies the vaginal environment and help to protect against invading pathogens. However, a 'normal' microbiome is often difficult, if not impossible, to characterise given that it varies in response to numerous variables, including pregnancy, the menstrual cycle, contraceptive use, diet, ethnicity, and stress. A Lactobacillus-depleted microbiome has been linked to a variety of adverse vaginal health outcomes, including preterm birth (PTB), bacterial vaginosis (BV), and increased risk of sexually transmitted infections. The latter two of these have also been associated with feminine intimate hygiene practices, many of which are practised without any evidence of health benefits. The most extensively studied practice is vaginal douching, which is known to cause vaginal dysbiosis, predisposing women to BV, pelvic inflammatory disease, and PTB. However, little is known of the impact that intimate hygiene practices and associated products have on the vaginal microbiome. This review aims to outline the major factors influencing the vaginal microbiome and common vaginal infections, as well as to summarise current research surrounding the impact of hygiene products and practices on the vaginal microbiome.

Evaluation of the efficacy of Lactobacillus-containing feminine hygiene products on vaginal microbiome and genitourinary symptoms in pre- and postmenopausal women: A pilot randomized controlled trial

As estrogen level decreases with aging, the vaginal mucosa gets thinner, and collagen amount decreases. In addition, the population of Lactobacillus in the vagina declines, increasing the risk of atrophic vaginitis, bacterial vaginosis, and genitourinary symptoms in the postmenopausal women. In this study, we evaluated the effects of Lactobacillus-containing feminine hygiene products on vaginal microbiome and genitourinary symptoms in pre- and postmenopausal women. This was a pilot randomized controlled trial in 35 premenopausal and 35 postmenopausal healthy women. For 4 weeks, treatment 1 group (14 premenopausal and 16 postmenopausal women) used the Lactobacillus-containing feminine soap and cream, and treatment 2 group (15 premenopausal and 14 postmenopausal women) used Lactobacillus-containing feminine gel in addition to soap and cream. The remaining 6 premenopausal and 5 postmenopausal women served as controls without using any products. We then compared the changes in the vaginal microbiota, genitourinary symptoms, and other related biomarkers after completion of treatment. Vaginal pH and pathogenic flora were reduced in both treatment groups compared to control group, which was more significant in the treatment 2 group of postmenopausal women. Genitourinary symptoms significantly improved in 60% of premenopausal women in treatment 1 group and 81.3% of postmenopausal women in treatment 2 group, compared to control group (0%, p = 0.043 and p<0.01 respectively). Overactive bladder symptom scores were significantly improved after using the products in eleven out of twelve postmenopausal women suspected of having overactive bladder. The use of Lactobacillus-containing feminine products was associated with improved vaginal ecosystem and urogenital health compared to control group, especially in those women using feminine gel.

Age-Related Changes, Influencing Factors, and Crosstalk Between Vaginal and Gut Microbiota: A Cross-Sectional Comparative Study of Pre- and Postmenopausal Women

Objective: The ideal vaginal environment is maintained by Lactobacillus species, which keep the vagina clean and free of infections, boost fertility and immunity. Age-related decline in estrogen affects Lactobacillus population, leading to dominance of nonoptimal species and increased diversity in vaginal microbiota. In this study, we compared the differences between the vaginal microbiota of pre- and postmenopausal women. We also examined the relationships between vaginal and gut microbiota, their relationships with sex hormones and equol-producing ability. Materials and Methods: This was a cross-sectional study of 35 premenopausal and 35 postmenopausal women (age range: 27-76 years). We compared parameters such as the composition of the gut and vaginal microbiota, vaginal pH, estradiol, follicular stimulating hormone, and urinary equol concentration. Results: In the vaginal microbiota of premenopausal women, Lactobacillus species constituted ∼71.98%, and nonoptimal species constituted ∼16.87%. They were 10.08% and 26.78%, respectively, in the vaginal microbiota of postmenopausal women. The proportion of Lactobacillus was significantly low, whereas microbial diversity and vaginal pH were significantly high (p < 0.0001) in postmenopausal women. The compositions of the vaginal microbiota were significantly different in pre- and postmenopausal women. However, such differences were not noticeable in the gut microbiota. Urinary equol production had no significant correlation with vaginal microbiota, although it had significant relationships with gut microbiota in postmenopausal women. In both groups, the proportions of vaginal Lactobacillus were inversely correlated with vaginal microbial diversity and vaginal pH. Conclusion: Postmenopausal women had significantly low Lactobacillus and high nonoptimal species in their vaginal flora, whereas such age-related differences were not identified in gut microbiota. Urinary equol concentration had significant correlation with gut microbiota in postmenopausal women only. This study was registered with the University Hospital Medical Information Network (UMIN) Clinical Trial Registry (Trial registration No.: UMIN000043944).

Recurrent Miscarriage: Diagnostic and Therapeutic Procedures. Guideline of the DGGG, OEGGG and SGGG (S2k-Level, AWMF Registry No. 015/050, May 2022)

Purpose The aim of this guideline is to standardize the diagnosis and therapy of recurrent miscarriage (RM) using evidence from the recent literature. This is done by using consistent definitions, objective evaluations and standardized treatment protocols.

Methods When this guideline was compiled, special consideration was given to previous recommendations in prior versions of this guideline and the recommendations of the European Society of Human Reproduction and Embryology, the Royal College of Obstetricians and Gynecologists, the American College of Obstetricians and Gynecologists and the American Society for Reproductive Medicine, and a detailed individual search of the literature about the different topics was carried out.

Recommendations Recommendations about the diagnostic and therapeutic procedures offered to couples with RM were developed based on the international literature. Special attention was paid to known risk factors such as chromosomal, anatomical, endocrinological, physiological coagulation, psychological, infectious and immune disorders. Recommendations were also developed for those cases where investigations are unable to find any abnormality (idiopathic RM).

Genital Microbiota and Outcome of Assisted Reproductive Treatment-A Systematic Review

The balance between different bacterial species is essential for optimal vaginal health. Microbiome includes the host genome along with microorganism genomes and incorporates the biotic and abiotic factors, reflecting the habitat as a whole. A significant difference exists in the composition and number of the human microbiota in healthy individuals. About one-tenth of the total body microbiota exists in the urogenital tract and these can be identified by microscopy and culture-based methods, quantitative PCR, next generation and whole genome sequencing. The trend of delaying the planning of pregnancy to a later age nowadays has resulted in magnifying the use of assisted reproductive treatment (ART). Hence, genital microbiota and its impact on fertility has generated immense interest in recent years. In this systematic review, we searched the available evidence on the microbiota of the genital tract in women undergoing ART and studied the outcomes of IVF in different microbial compositions. Despite the inconsistency of the studies, it is evident that vaginal, cervical and endometrial microbiota might play a role in predicting ART outcomes. However, there is no clear evidence yet on whether the diversity, richness, quantity, or composition of species in the maternal genital tract significantly affects the outcomes in ARTs.

Improving analysis of the vaginal microbiota of women undergoing assisted reproduction using nanopore sequencing

PURPOSE

Subclinical alterations of the vaginal microbiome have been described to be associated with female infertility and may serve as predictors for failure of in vitro fertilization treatment. While large prospective studies to delineate the role of microbial composition are warranted, integrating microbiome information into clinical management depends on economical and practical feasibility, specifically on a short duration from sampling to final results. The currently most used method for microbiota analysis is either metagenomics sequencing or amplicon-based microbiota analysis using second-generation methods such as sequencing-by-synthesis approaches (Illumina), which is both expensive and time-consuming. Thus, additional approaches are warranted to accelerate the usability of the microbiome as a marker in clinical praxis.

METHODS

Herein, we used a set of ten selected vaginal swabs from women undergoing assisted reproduction, comparing and performing critical optimization of nanopore-based microbiota analysis with the results from MiSeq-based data as a quality reference.

RESULTS

The analyzed samples carried varying community compositions, as shown by amplicon-based analysis of the V3V4 region of the bacterial 16S rRNA gene by MiSeq sequencing. Using a stepwise procedure to optimize adaptation, we show that a close approximation of the microbial composition can be achieved within a reduced time frame and at a minimum of costs using nanopore sequencing.

CONCLUSIONS

Our work highlights the potential of a nanopore-based methodical setup to support the feasibility of interventional studies and contribute to the development of microbiome-based clinical decision-making in assisted reproduction.

Microbiology of Human Follicular Fluid and the Vagina and Its Impact on in Vitro Fertilization Outcomes

PURPOSE

The present study aimed to identify microorganisms in follicular fluids and to investigate their association with in vitro fertilization (IVF) outcomes.

MATERIALS AND METHODS

This study was conducted as a prospective study of 49 infertile females undergoing IVF/intracytoplasmic sperm injection cycles between 2013 and 2016. Paired follicular fluid and vaginal secretions were collected on the day of ovum pick up and were cultured to detect microorganisms.

RESULTS

Fifteen women (30.6%) had no microorganisms in follicular fluid or vaginal swabs, 23 (46.9%) had microorganisms on vaginal swab alone, 3 (6.1%) had microorganisms in follicular fluid alone, and 8 (16.3%) had microorganisms in both follicular fluid and vaginal swabs. The same microorganisms were detected in both the follicular fluid and vaginal swabs of three women, while different microorganisms were detected between follicular fluid and vaginal swabs in five women. Follicular fluid microorganisms were not associated with embryo quality or clinical pregnancy rates during IVF cycles. However, significantly decreased implantation rates (9.1% vs. 29.4%, p=0.031) and clinical pregnancy rates on embryo transfer day 5 (0% vs. 83.3%, p=0.048) were observed in the group that was positive for vaginal pathogens.

CONCLUSION

Follicular fluid contains microorganisms that can differ from those in the vagina of the same women; however, they do not appear to be associated with embryo quality or clinical pregnancy rates in IVF cycles. In contrast, vaginal pathogens were found to be associated with worse implantation rates and clinical pregnancy rates in IVF cycles.

The relationship between vaginal pH and bacterial vaginosis as diagnosed using qPCR in an asymptomatic subfertile population

PURPOSE

Bacterial vaginosis (BV) is a dysbiosis of the vaginal microbiome and a condition found in 20-30% of all women. Literature describing the possible link between BV and subfertility is increasing. Newer techniques such as quantitative polymerase chain reactions (qPCR) detect BV more accurately than traditional methods but come with high costs. The association between pH and BV as diagnosed using traditional methods is well-established in a symptomatic population. This study is the first to investigate the association between pH and BV diagnosed by qPCR in an asymptomatic subfertile population and to examine the usefulness of pH as a means of cost reduction.

METHODS

Data of 170 pH-qPCR combinations were used from a prospective cohort study examining bacterial vaginosis in a subfertile population. 102 women received a vaginal swab and pH measurement at baseline and subsequent advanced reproductive technology (ART) treatments. The swabs are analysed using the AmpliSens^®Florocenosis/Bacterial vaginosis-FRT qPCR kit.

RESULTS

pH is strongly associated with BV as diagnosed by qPCR (OR 3.06, p = 0.000, CI 1.65-5.68). The cut-off point for pH ≥ 4.7 maximised diagnostic performance [AUC 0.74 (CI 0.66-0.83), sensitivity 76%] and reduced costs by 60%.

CONCLUSION

This study shows that the vaginal pH for a multi-ethnic, asymptomatic population of women attending fertility clinics is strongly associated with BV qPCR outcome. Using the cut-off of pH of 4.7 has a high sensitivity for diagnosis of BV by qPCR and can be achieved at a cost reduction of 60%.

Young fecal transplantation mitigates the toxicity of perfluorobutanesulfonate and potently refreshes the reproductive endocrine system in aged recipients

The aging process leads to the gradual impairment of physiological functions in the elderly, making them more susceptible to the toxicity of environmental pollutants. In this study, aged zebrafish were first transplanted with the feces from young donors and subsequently exposed to perfluorobutanesulfonate (PFBS), an emerging persistent toxic pollutant. The interaction between young fecal transplant and PFBS inherent toxicity was investigated, focusing on reproductive performance and the underlying endocrine mechanism. The results showed that PFBS single exposure increased the percentage of primary oocytes in aged ovaries, implying a blockage of oogenesis. However, transplantation of young feces completely abolished the effects of PFBS and promoted oocyte growth, as inferred by the obviously lower percentage of primary oocytes, accompanied by a higher percentage of cortical-alveolar oocytes. Measurement of sex hormones found that PFBS significantly increased the blood concentration of estradiol and disrupted the balance of sex hormones in the elderly, which were, however, efficiently ameliorated by young fecal transplantation. Based on gene transcription along the hypothalamic-pituitary-gonadal axis, hierarchical clustering analysis showed similar profiles of the reproductive endocrine system between young zebrafish and their aged counterparts transplanted with young feces, implying that young fecal transplantation might refresh the endocrine system of aged recipients, regardless of PFBS exposure. The increased transcription levels of mRNAs encoding vitellogenin, activinBA, and membrane bound progestin receptors would cooperatively enhance the growth and maturation of oocytes in the ovaries of aged zebrafish receiving young fecal transplantation. Overall, the findings highlighted the potent efficacy of young fecal transplantation to improve the reproductive function of the elderly and to mitigate the endocrine disruption of an environmental pollutant. These findings are expected to broaden our understanding of the efficacy, mechanisms, and application of fecal transplantation.

Vaginal Microbiome in Reproductive Medicine

The human microbiome has been given increasing importance in recent years. The establishment of sequencing-based technology has made it possible to identify a large number of bacterial species that were previously beyond the scope of culture-based technologies. Just as microbiome diagnostics has emerged as a major point of focus in science, reproductive medicine has developed into a subject of avid interest, particularly with regard to causal research and treatment options for implantation failure. Thus, the vaginal microbiome is discussed as a factor influencing infertility and a promising target for treatment options. The present review provides an overview of current research concerning the impact of the vaginal microbiome on the outcome of reproductive measures. A non-Lactobacillus-dominated microbiome was shown to be associated with dysbiosis, possibly even bacterial vaginosis. This imbalance has a negative impact on implantation rates in assisted reproductive technologies and may also be responsible for habitual abortions. Screening of the microbiome in conjunction with antibiotic and/or probiotic treatment appears to be one way of improving pregnancy outcomes.

Endometrial compaction is associated with increased clinical and ongoing pregnancy rates in unstimulated natural cycle frozen embryo transfers: a prospective cohort study

PURPOSE

To investigate the association between endometrial compaction and pregnancy rates in unstimulated natural cycle frozen embryo transfers.

DESIGN

A single-center prospective cohort study. Endometrial thickness by transvaginal ultrasound and blood progesterone levels on the day of ovulation and the day of embryo transfer were evaluated in patients undergoing natural cycle frozen embryo transfer. Compaction was defined as > 5% decrease in endometrial thickness between ovulation day and day of transfer. Clinical and ongoing pregnancy rates in cycles with and without compaction were compared.

RESULTS

Seventy-one women were included, of which 44% had endometrial compaction, with similar rates when subdividing the patients by day of transfer (day 3 or day 5). Clinical and ongoing pregnancy rates were higher in the compaction group compared to the non-compaction group (0.58 vs. 0.16, P < 0.001; 0.52 vs. 0.13, P < 0.001 respectively). Subdividing by degree of compaction > 10% and > 15% revealed similar pregnancy rates as > 5%, with no added benefit to higher degrees of compaction.

CONCLUSIONS

About half the patients in our study undergoing unstimulated natural cycle frozen embryo transfer experienced compaction of the endometrium, occurring as early as day 3 post-ovulation. This was significantly correlated with increased clinical and ongoing pregnancy rates.

Endometrial factors in the implantation failure spectrum: protocol of a MUltidisciplinary observational cohort study in women with Repeated Implantation failure and recurrent Miscarriage (MURIM Study)

INTRODUCTION

Women with repeated implantation failure (RIF) and unexplained recurrent miscarriage (RM) are proposed to be at opposite ends of the implantation spectrum, with RM representing an overly receptive endometrium (implantation of genetically aberrant or poor-quality embryos) versus RIF representing an overly selective endometrium (no implantation even with good quality embryos). In both cases, often no explanation for reproductive failure can be found and although promising add-on treatments have been introduced, therapeutic options are frequently limited to supportive care. Both RM and RIF are multifactorial and research indicates that the interplay between steroidogenesis, uterine natural killer (uNK) cells and the microbiome determine the capacity of the endometrium to be a biosensor for invading embryos. Our objective is to elucidate whether there is a difference in endometrial receptivity parameters (ie, steroid metabolism, uNK cells and the microbiome) between women aged 18-38 years with reproductive failure (RIF and RM), and fertile controls.

METHODS AND ANALYSIS

Single-centre, observational cohort study. Endometrial biopsies, vaginal swabs and peripheral blood will be collected during the window of implantation and menstrual blood in the subsequent menstruation. The study parameters are the steroid profile (steroid levels and mRNA levels, protein expression and activity of steroid enzymes) in endometrial tissue and peripheral blood, as well as the activating or inhibitory phenotype of uNK cells based on receptor expression in menstrual blood and endometrial tissue and determination of the vaginal and endometrial microbiome using the inter spacer bacterial profiling technique.

ETHICS AND DISSEMINATION

The protocol is approved by the local medical ethical review committee at the Maastricht University Medical Centre. Findings from this study will be shared with the academic and medical community and the patient organisations to optimise and individualise medical care of patients with implantation failure and miscarriages.

TRIAL REGISTRATION NUMBER

NTR7571, registered 28 February 2019.