The untapped potential of vaginal microbiome diagnostics for improving women's health.

The vaginal microbiome is a complex and dynamic ecosystem of microorganisms that plays a crucial role in maintaining vaginal health. Its composition is influenced by hormonal fluctuations occurring during different stages of a woman’s life, such as prepuberty, the reproductive years, and postmenopause ( Hickey et al., 2012 ; Chen et al., 2021 ). During the reproductive years, cyclical hormonal fluctuations associated with the menstrual cycle drive shifts in the vaginal microbiome ( Hickey et al., 2012 ). The vaginal microbiome’s ability to adapt and return to a state of homeostasis is essential for protecting against infections and maintaining overall vaginal health ( Chee et al., 2020 ). Disruption of this delicate balance can lead to dysbiosis, which may adversely affect reproductive health and contribute to conditions such as infertility, miscarriage, gynaecological cancers, premature birth, and disease ( Merone et al., 2022 ). Despite advances in research, our understanding of the vaginal microbiome and its interactions with the host remains limited. Historically, medical studies have excluded female participants and research data have been collected from men and subsequently generalised to women ( Merone et al., 2022 ). Geller et al. analysed 86 randomised controlled trials across nine journals and found female representation to be just 37% ( Geller et al., 2011 ). The underrepresentation of women in clinical trials limits understanding of gender differences in drug treatments, potentially leading to harmful outcomes. This bias can result in less effective treatments for women and overlooked side effects due to factors such as hormonal fluctuations, pregnancy, and menopause. Without adequate representation, safety profiles may be misunderstood, and women may not receive the correct diagnosis or treatment. A report conducted by the Global Health Alliances in 2014 suggested that neglect in medical research and funding is directly responsible for delayed diagnosis, severe disease progression, and premature death in women ( It’s about time to focus on women’s health, 2023 ). Fewer studies focusing on women’s health issues will lead to slower development of diagnostics and treatments specifically designed to address women’s specific health needs. This can hinder progress in areas such as reproductive health, menopause, and certain cancers, including breast, cervical and ovarian cancer. Numerous microbiome studies highlight the need for personalised healthcare approaches that account for individual variations ( Kashyap et al., 2017 ; Ratiner et al., 2024 ). Vaginal microbiome diagnostics show promise in various applications, including early detection of infections, more accurate diagnosis of gynaecological conditions, and improved reproductive health outcomes by assessing fertility, pregnancy, and cancer risks. Personalised treatment plans can also be tailored based on these diagnostics. In this review, we evaluate the potential of different rapid diagnostic tools, current advancements in vaginal microbiome diagnostics, and their prospects.

At this time, women will be spending 40% of their lives in the postmenopausal state, with 50%–70% of postmenopausal women reporting symptomatic genitourinary syndrome of menopause (GSM) ( Da Silva et al., 2021 ). GSM is the accepted term used to describe the broad range of signs and symptoms affecting the genitourinary tract, which occur due to the loss of endogenous sex steroids associated with menopause ( Portman et al., 2014 ). It has been observed that, in postmenopausal women, there is a decrease in Lactobacillus species and a higher abundance of genera including Anaerococcus , Peptoniphilus , and Prevotella , which could play a role in the clinical presentation of GSM ( Gliniewicz et al., 2019 ). Consequently, a microbiome-based diagnostic test that monitors the abundance of Anaerococcus , Peptoniphilus , and Prevotella species may offer valuable insights into the pathogenesis and progression of GSM. A Lactobacillus -dominant vaginal microbiome is vital in maintaining an acidic pH and protecting against bacterial pathogens ( Taithongchai et al., 2024 ). Postmenopausal women are noted to have high vaginal pH, which results in the loss of local vaginal defences against harmful microorganisms, predisposing them to infections such as urinary tract infections (UTIs) ( Harding et al., 2024 ). The prevalence of UTIs is 20% in women over 65, compared with 11% in the general population ( Chu and Lowder, 2018 ). While more studies are starting to emerge, there remains a lack of knowledge about the composition of the vaginal microbiota across the stages of menopausal transition, its interactions with hormones such as oestrogen, and its associations with infections. Evaluating changes in the vaginal microbiota across a woman’s lifespan can provide valuable insight for healthcare providers to help better understand menopausal wellness and its associated morbidities.

The lack of precision in current diagnostic tools for women’s health remains a significant obstacle to timely detection, resulting in delayed diagnoses and suboptimal treatment outcomes. To bridge this gap, a shift is needed to prioritise gender-specific research, refine diagnostic methodologies, and enhance clinician training. The vaginal microbiome represents a promising area in women’s health diagnostics, offering potential biomarkers that could revolutionise early detection and intervention. While further research is needed to strengthen the links between alterations in the vaginal microbiome and specific conditions, as discussed previously, several studies have already demonstrated the clinical value of microbiome-based diagnostics. For example, cervicovaginal fluid (CVF) samples from pregnant women have been analysed to identify bacterial markers predictive of preterm birth, with the potential to develop models that predict preterm birth when integrated with clinical data ( Park et al., 2021 ; Park et al., 2022 ). The success of HPV vaccination and screening programmes in preventing cervical cancer exemplifies the critical role of pursuing biomarker-driven diagnostics in public health, allowing health concerns to be identified at their earliest stages when treatment can be most effective, and lead to better patient outcomes. To advance this effort, we must address the persistent underrepresentation of women in clinical trials and ensure that ongoing research includes sufficiently large sample sizes. This is crucial for uncovering novel biomarkers and therapeutic targets within the vaginal microbiome, allowing for more effective diagnostic tools and personalised treatments. The incorporation of microbiome diagnostics into clinical workflows represents a critical advancement in women’s health, offering the potential to enhance existing diagnostic tools and support the development of novel POCT strategies. Traditional diagnostic methods, such as Amsel’s criteria or Nugent scoring, commonly used to diagnose BV, are often limited by subjectivity and variability. In contrast, emerging molecular-based assays offer a more accurate and comprehensive analysis of the vaginal microbiota. These approaches provide greater insight into the microbial community, enabling more precise identification of dysbiosis and associated reproductive health risks. To ensure the successful clinical application of microbiome-based diagnostics, rigorous clinical trials must validate microbiome diagnostics and, along with appropriate standardisation, strengthen the knowledge and evidence base for their use in clinical settings, ensuring regulatory compliance of such approaches and optimising their integration into clinical workflows to enhance women’s reproductive health and quality of life.

While the need for improved understanding of how the vaginal microbiome has an impact on women-specific issues such as infertility or gynaecological cancers, a major hurdle in covering this knowledge gap is the variability in microbiome data across studies, as well as the insufficient research in women’s health. This observed variability results from both the clinical trial design and the methodologies used. Current methods used to study the composition of the microbiome introduce biases at different steps of analysis; therefore, the adoption of vaginal microbiome-specific reference reagents (RRs) is essential to enhance the reproducibility and comparability of research findings across studies worldwide. This effort has been initiated by the Medicines and Healthcare Products Regulatory Agency (MHRA) with the development of the WHO gut microbiome-specific International RRs, while WHO-endorsed vaginal-specific microbiome RRs which will support the development, optimisation, and implementation of vaginal microbiome diagnostics and the harmonisation and reproducibility of clinical studies ( Sergaki et al., 2022 ; Anwar et al., 2023 ). Furthermore, to progress in the field of vaginal microbiome diagnosis, we need to strengthen the knowledge base on the factors associated with changes to the microbiome and ensure that all relevant variables are appropriately captured in clinical studies. Numerous factors, such as age, hormone status (menstrual cycle, birth control pills, menopause, pregnancy), infections, and sexual behaviours, play a significant role in the variability of the vaginal microbiome and the clinical trial observations ( White et al., 2011 ; Huang et al., 2014 ). A robust clinical trial design with comprehensive metadata will allow for a deeper understanding of how these factors influence the vaginal microbiome and will help to identify the necessary considerations for ensuring an accurate diagnosis.

While women’s health, and particularly the vaginal microbiome, are under-researched, the potential of vaginal microbiome diagnostics in improving women’s health is substantial, offering a promising avenue for personalised healthcare through noninvasive, patient-friendly, and POCT options ( Figure 1 ). The future of vaginal microbiome health in clinical practice will leverage emerging technologies for more precise and personalised diagnosis and treatment. As understanding of the vaginal microbiome deepens, treatments tailored to an individual’s unique microbiome profile provide a potential avenue for the development of innovative treatments. Emerging evidence suggests that specific bacterial species may be associated with distinct disease states. However, the lack of standardisation currently limits our ability to reliably identify consistent microbial associations across studies. To advance the diagnostic potential of vaginal microbiome profiling, it is crucial to conduct further research focusing on standardised and optimised protocols to improve data comparability, enhance reproducibility, and support the development of a robust, disease-specific microbial biomarker database. By accurately analysing the composition and diversity of the vaginal microbiome, these diagnostics can enable early detection of conditions such as BV, STIs, and more complex issues such as pre-term birth, infertility and gynaecological cancers. There is a critical need to accelerate the development of improved techniques for providing accurate and early diagnoses of conditions affecting women’s health. The implementation of vaginal microbiome diagnostics into clinical practice holds the potential to transform women’s health, providing more precise, early, effective, and personalised care. Potential of vaginal microbiome diagnostics in advancing women’s health (The icons on the right were obtained using freely available resources from Freepik, and the image on the left was generated with ChatGPT 4.0).