Effect of pelvic floor muscle training on pelvic floor muscle morphometry in subjects with pelvic organ prolapse: a systematic review and meta-analysis

Background Pelvic organ prolapse (POP) is common among women and is associated with bladder, bowel, and sexual dysfunction, reducing quality of life. Pelvic floor muscle training (PFMT) is recommended as a first-line conservative therapy, but its effects on pelvic floor muscle (PFM) morphometry remain unclear. This is the first systematic review and meta-analysis to evaluate the effects of PFMT on PFM morphometric parameters in women with POP .

A comprehensive search of PubMed/MEDLINE, Scopus, the Cumulative Index to Nursing and Allied Health Literature (CINAHL), Web of Science, the Cochrane Library, and the Physiotherapy Evidence Database (PEDro) was conducted. The study was conducted and reported in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The search strategy covered all records from database inception to July 9, 2025. Randomized controlled trials (RCTs) and clinical trials assessing PFMT effects on PFM morphometry were included. Methodological quality was assessed using the PEDro scale. Meta-analyses were performed using random- effects and fixed-effects models.

Eight studies with 579 women (POP stages I–III) were included. Meta-analyses based on excellent to low quality evidence demonstrated significant reductions in levator hiatus area (LHA) at rest (MD = − 1.97; 95% CI: −2.79 to − 1.15; p < 0.0001; 3 studies) and, based on good to low quality evidence, during the Valsalva maneuver (MD = − 2.30; 95% CI: −3.36 to − 1.25; p < 0.0001; 2 studies). Furthermore, excellent to low quality evidence indicated that PFMT improved bladder neck position (MD = 0.16; 95% CI: 0.08 to 0.23; p < 0.0001; 3 studies). Narrative synthesis suggested improvements in PFM strength, while effects on the POP stage were inconsistent across studies. Based on PEDro ratings, the included studies comprised three excellent, one good, two moderate, and two low-quality trials.

PFMT may improve PFM morphometry, POP stage, and muscle strength in women with POP . However, the evidence remains limited due to the small number of studies, the low quality of some studies, and the inclusion Effect of pelvic floor muscle training on pelvic floor muscle morphometry in subjects with pelvic organ prolapse: a systematic review and meta-analysis Shabnam ShahAli1, Kari Bø2, Anahita Hejazi3, Hamideh Hashemi1 and Ghazal Kharaji1* Page 2 of 12 ShahAli et al. BMC Women's Health (2025) 25:542

Pelvic organ prolapse (POP) is a prevalent condition among women, characterized by the downward dis - placement of one or more pelvic structures, including the anterior or posterior vaginal wall, the uterus, or the vaginal apex [ 1]. The etiology of POP is multifactorial, with advancing age and vaginal childbirth identified as the most significant contributing factors. Reported rates of stage II or higher POP range from 18% to 56% within 3 to 6 months postpartum, with natural remission to be expected [ 2]. Among middle-aged and older women, especially those over 50, the prevalence is estimated to be between 30% and 60% [ 3, 4]. POP can negatively impact bladder, bowel, and sexual function, often leading to con- siderable discomfort and a wide range of symptoms, such as a sensation of vaginal bulging, low back pain, increased urinary frequency, and a sense of incomplete bowel evacuation [1]. These symptoms may interfere with daily activities and significantly reduce the quality of life in affected women [ 5, 6]. Beyond individual health, POP is a major public health concern with broader implications for women’s well-being and socioeconomic burden [7, 8]. Current therapeutic approaches for POP include surgi - cal and conservative management, most notably pelvic floor muscle training (PFMT) and pessary. However, the long-term outcomes of surgical treatment remain subop - timal. Recurrence of POP following any POP surgery is common, with reported recurrence rates ranging from 6% to 30% [ 9, 10]. Furthermore, the invasive nature of surgery may lead to postoperative complications such as pelvic pain, dyspareunia, and persistent vaginal bleeding or discharge [ 9]. In contrast, growing evidence supports PFMT as an effective conservative treatment for reduc - ing POP symptoms and severity, and it is increasingly recommended as the first-line therapy for women with POP [ 11– 14]. Two primary hypotheses have been pro - posed to explain the mechanisms by which PFMT may exert its therapeutic effects. The first hypothesis centers on behavioral modification, specifically, teaching women to perform voluntary pelvic floor muscle (PFM) con - tractions during activities that increase intra-abdominal pressure (e.g., coughing), which may help prevent POP exacerbation [15, 16]. Although this may provide imme - diate symptomatic relief, it is unlikely to induce lasting anatomical changes. The second hypothesis suggests that regular PFMT over time results in elevation of the pelvic organs and a reduction in the size of the levator hiatus area (LHA), thereby enhancing structural support and promoting more effective automatic pelvic floor func - tion [ 17, 18]. These morphological improvements may address the underlying structural deficits contributing to POP , thereby providing a more sustained therapeutic benefit that extends beyond symptom management. Previous studies have identified several morphological differences in the pelvic floor structures of women with POP compared to those without the condition. These alterations include an increased LHA [ 19, 20], a low - ered position of the bladder neck and rectal ampulla [ 21, 22], and reduced thickness of the levator ani muscle [ 23, 24]. Emerging evidence suggests that PFMT may posi - tively influence these morphological parameters [ 25– 28]. Establishing the efficacy of such interventions is essential for their clinical recommendation. If PFMT can induce morphological improvements within the pelvic floor, it may help modify the underlying pathophysiology of POP and thereby strengthen its role as a rehabilitative intervention. To date, only one narrative review has examined the effects of PFMT on PFM morphology in women with stress urinary incontinence and POP [ 17]. Although that review concluded that PFMT may alter PFM morphology, only two of the ten included studies specifically assessed women with POP , and most findings were reported for mixed populations of women with stress urinary inconti - nence and POP . Thus, it remains unclear whether PFMT can induce morphological improvements in the PFM in women with POP . Therefore, the present study aims to systematically synthesize and critically appraise evidence from randomized controlled trials (RCTs) and clinical trials that have specifically evaluated the effects of PFMT on PFM morphometry in women diagnosed with POP .

This systematic review and meta-analysis was conducted and reported in accordance with the Preferred Report - ing Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines [ 29]. The review protocol was reg - istered in the PROSPERO database (registration number: CRD420251021705). The study included RCTs and clini - cal trials that assessed the effects of PFMT on PFM mor - phometry in individuals diagnosed with POP . of women with POP stages I–III. High-quality RCTs are needed to address these limitations and identify patient subgroups most likely to benefit. Trial registration PROSPERO registration number CRD420251021705.

Pelvic organ prolapse, Pelvic floor muscle training, Morphometry, Levator hiatus, Bladder neck position, Pelvic floor rehabilitation, Systematic review, Meta-analysis Page 3 of 12 ShahAli et al. BMC Women's Health (2025) 25:542 Search strategy The electronic databases searched for relevant published literature included PubMed/MEDLINE, Scopus, the Cumulative Index to Nursing and Allied Health Litera - ture (CINAHL), Web of Science, the Cochrane Library, and the Physiotherapy Evidence Database (PEDro). All databases were systematically searched from their incep - tion through July 9, 2025. Additionally, the reference lists of all articles selected for critical appraisal, as well as rel - evant grey literature, were screened to identify further eligible studies. The complete search strategies for MED - LINE, Scopus, and Web of Science are detailed in Supple- mentary 1. The eligibility criteria were defined using the PICOS framework as follows: Population: Adult women (aged ≥ 18 years) diagnosed with any stage of POP according to the Pelvic Organ Prolapse Quantification System (POP- Q) [30]. Intervention: Any form of PFMT, including various instructional methods, contraction types, number of contractions, and whether the training was supervised or unsupervised. Interventions could be delivered alone or in combination with adjunctive modalities, such as electrical stimulation or biofeedback. Comparator: Any other intervention or no treatment; Outcomes: The primary outcomes in this study were measures of PFM morphometry assessed by ultrasound imaging and/or Magnetic resonance imaging (MRI), including thickness, cross-sectional area, and length of the levator ani muscle, pelvic organ position, and LHA dimensions. Furthermore, in the included studies, POP stage and PFM strength were assessed as secondary outcomes. Study design: RCTs and clinical trials (pre-post test studies and studies with non-randomized control groups). Only peer-reviewed full-text articles published in English were included. Studies were excluded from the systematic review for the following reasons: inclusion of participants using a pessary; lack of analysis or clear description of the variables of interest; and use of PFMT as an adjunct to surgical intervention. Other study types, including reviews, cross-sectional studies, case series, quasi-exper - imental designs, and commentaries, were also excluded. Study selection and data extraction One reviewer performed the database searches and eliminated duplicate records using EndNote X9.1 soft - ware. Subsequently, two independent reviewers screened the titles and abstracts to determine the relevance of the studies based on the established inclusion criteria. Full texts of potentially relevant studies were then evaluated independently by the same two reviewers. Any discrep - ancies between the reviewers were resolved through dis - cussion with a third reviewer. Data extraction was performed independently by two reviewers (GK and HH). The existing disagreements were resolved via a consensus meeting by the third reviewer (SS). The following information was extracted from the included studies: authors, publication year, country, study design, sample characteristics (age, mean age), POP stage, summary of interventions in treatment and con - trol group, outcomes and measurements used, and main results. To obtain missing data relevant to the analysis, email requests were sent to the corresponding authors of the eligible studies. However, no responses were received. Methodological quality assessment The methodological quality of the included studies was independently evaluated by two reviewers (GK and HH) using the PEDro scale. Any discrepancies in scoring were resolved through discussion with a third reviewer (SS). The PEDro scale comprises 11 items: the first item assesses external validity but is not included in the total score, while the remaining 10 items evaluate internal validity. Each item is scored as 1 point if the criterion is met (“yes”) and 0 if it is not met (“no”). The overall qual- ity score is calculated by summing the points from the ten scored items. Studies were categorized based on their total score as follows: excellent quality (scores 9–10), good quality (scores 6–8), moderate quality (scores 4–5), and low quality (scores below 4) [31]. Statistical analysis All analyses were conducted using Stata MP version 17 (StataCorp, College Station, TX, USA). Statistical het - erogeneity among studies was assessed using the I² sta - tistic, with values exceeding 50% indicating substantial heterogeneity. When statistical heterogeneity was low (I² < 50%), a fixed-effect inverse-variance model was employed. In the presence of substantial heterogeneity (I² ≥ 50%), a random-effects model using the restricted maximum likelihood (REML) method was applied to minimize potential bias [ 32]. Accordingly, the random- effects REML model was used to evaluate the effective - ness of PFMT on LHA at rest and bladder neck position, whereas the fixed-effect inverse-variance model was applied for assessing PFMT effectiveness during the Val - salva maneuver. Effect sizes were calculated as mean differences between baseline and post-intervention values. Forest plots with 95% confidence intervals (CI) were gener - ated to visualize pooled effects. The magnitude of effect Page 4 of 12 ShahAli et al. BMC Women's Health (2025) 25:542 sizes was interpreted using the following thresholds: 4.00: almost perfect [33]. Assessment of publication bias and meta-regression analysis was not possible due to the small number of included studies. A p-value of less than 0.05 was consid - ered indicative of potential publication bias.

An initial search across all databases yielded 206 stud - ies. Following the removal of duplicates, 98 citations remained. Of these, 87 were excluded based on title and

screening. Eleven articles were retrieved for full- text assessment, resulting in the exclusion of three stud - ies. Consequently, eight studies met the inclusion criteria and were incorporated into this systematic review and meta-analysis [5, 25– 28, 34– 36]. The study selection pro- cess is illustrated in the PRISMA flowchart (Fig. 1). Among the eight included studies investigating mor - phological changes following PFMT in women with POP , three were clinical trials [ 5, 27, 36] and five were RCTs [25, 26, 28, 34, 35]. Notably, two publications originated from a single RCT, reporting different outcomes [ 25, 26]. Of the three clinical trials, two employed a pre–post design without a control group [ 27, 36], while one study included two non-randomized groups [5]. The included studies were analyzed using three meta- analyses and two narrative syntheses. The first meta- analysis included three studies that evaluated the effects of PFMT on the LHA at rest [5, 27, 37]. The second meta- analysis incorporated two studies examining the effects of PFMT on the LHA during the Valsalva maneuver [ 5, 27], and the third meta-analysis included two studies on the effects of PFMT on the bladder neck position [27, 35]. In addition, narrative systematic reviews were conducted to summarize the effects of PFMT on the POP stage [ 25, 27, 35, 36] and PFM strength [25– 28, 35, 36]. Fig. 1 Preferred reporting items for systematic reviews and meta-analysis (PRISMA) flow diagram mapping the review Page 5 of 12 ShahAli et al. BMC Women's Health (2025) 25:542 Participants The studies collectively included 579 women diagnosed with POP , with participant ages ranging from 29.5 to 67 years. Four of the eight studies specifically included postpartum women [ 5, 27, 28, 35]. The study popula - tions consisted of individuals with POP grades I, II, and III; however, none of the studies examined the effects of PFMT on the morphological characteristics of women with grade IV POP . PFMT characteristics The duration of the PFMT interventions ranged from 5 weeks to 6 months. All studies incorporated three sets of daily PFMT, performed at or near maximal contrac - tion intensity. Adherence to the prescribed regimen was reported in five studies, all of which indicated high com - pliance levels [5, 25, 26, 35, 36]. The most common train- ing frequency was 8 to 12 voluntary contractions per set. In six trials, the duration of each contraction hold ranged from 6 to 10 s [ 5, 25– 28, 34– 36], while three studies did not specify the contraction hold duration [ 25, 26, 35]. The rest interval between contractions ranged from 2 to 10 s in four studies [5, 27, 28, 36]. Regarding body positioning during PFMT, three stud - ies instructed participants to perform exercises in lying, sitting, and standing positions [ 25, 26, 34]; one study allowed unrestricted positioning [ 5]; and four studies did not report the participants’ exercise posture [ 28, 35, 36]. PFMT was performed at home across all studies. All but three studies [ 27, 28, 34] reported that participants received supervised sessions in combination with home exercise during at least some of the training sessions. In five studies, PFMT was combined with additional conservative interventions such as the knack technique [25, 26], Hypopressive exercise [34], biofeedback, or elec- trical stimulation [ 5, 27, 28], whereas in two studies [ 35, 36] PFMT was performed as a standalone intervention. Details of each of the included studies are in Table 1. Methodological quality The risk of bias among the included studies is presented in Fig. 2. According to the PEDro scale, the methodologi- cal quality of the studies ranged from low to excellent. Specifically, three studies were rated as excellent [ 25, 26, 35], one as good [ 5], two as moderate [ 28, 34], and two as low quality [ 27, 36]. None of the studies implemented blinding of participants or therapists administering the interventions. Assessor blinding was reported in three studies [ 25, 26, 35]. All studies scored positively on the items related to the specification of eligibility criteria and the reporting of between-group statistical comparisons. Outcomes Primary outcomes The LHA during the rest position Three studies assessed the effects of PFMT on LHA at rest using transperineal ultrasound imaging [ 5, 27, 37]. The pooled analysis of these studies demonstrated a sta - tistically significant reduction in LHA favoring PFMT, with a mean difference (MD) of − 1.97 (95% CI: −2.79 to −1.15; p < 0.0001) (Fig. 3). Moderate heterogeneity was observed among the studies (T² = 0.24; I² = 46.88%; p = 0.166). The LHA during the valsalva maneuver Two studies evaluated the effects of PFMT on bladder neck position using transperineal ultrasound imaging [5, 27]. The meta-analysis of these studies demonstrated a statistically significant reduction in LHA in favor of PFMT, with a MD of − 2.30 (95% CI: −3.36 to − 1.25; p < 0.0001) (Fig. 4). However, heterogeneity among the included studies was substantial (I² = 90.47%; p = 0.001). Bladder neck position Three studies investigated the effects of PFMT on blad - der neck position using transperineal ultrasound imaging [25, 27, 35]. One RCT that was not included in the meta- analysis due to insufficient data reported a significantly greater cranial elevation of the bladder neck in the PFMT group compared to the control group [ 25]. Similarly, the meta-analysis of two studies [ 27, 35] demonstrated a sig - nificant overall effect in favor of PFMT, with a MD of 0.16 (95% CI: 0.08 to 0.23, p < 0.0001) (Fig. 5). The heteroge- neity across the included studies was trivial (I² = 0.00%; p = 0.001). Secondary outcomes POP stage Four studies evaluated the effects of PFMT on POP stage improvement, as defined by the Pelvic Organ Pro - lapse Quantification System (POP-Q). One RCT study reported a significantly higher proportion of women in the PFMT group who improved by one POP-Q stage compared to the control group [ 25]. Two non-random - ized clinical trials demonstrated significant improve - ments in the POP stage following PFMT relative to baseline [27, 36]. In contrast, one RCT found no signifi - cant difference in POP stage improvement between the PFMT and control groups [35]. Meta-analysis was not feasible due to limitations in data reporting across the included studies. One study reported outcomes using medians rather than means [36], one study did not provide numerical data [ 35], and the other reported only the number of participants who improved in each group [25]. Page 6 of 12 ShahAli et al. BMC Women's Health (2025) 25:542

Area Study design and population Samples number (mean age) Intervention description Outcomes Ultrasound imaging technique

Intervention Control Inter- vention (duration) Control (duration) Braekken et al. 2010 [25] Norway RCT (not postpartum) 59 (49.4) 50 (48.3) The Knack + PFMT (3 sets of 8–12 close to maximum contraction, daily for 6 months) The knack (NR) -POP stage - Bladder and rectum position -Symptoms - PFM strength and endurance Transperineal The interven- tion group had signifi- cantly better improvement in all the measured out- comes after intervention Braekken et al. 2010 [26] Norway RCT (not postpartum) 59 (49.4) 50 (48.3) The knack + PFMT (3 sets of 8–12 close to maximum contraction, daily for 6 months) + booklet The knack (NR) - PFM strength -Bladder and rectum position -PFM thickness -LHA Transperineal The interven- tion group had signifi- cantly better improvement in all the measured out- comes after intervention Bernardes et al. 2012 [34] Brazil RCT (not postpartum) Group I: 21 (51.9) Group II: 21(56.7) 16 (58.7) Group I: PFMT (3 sets of 8–12 close to maximum contraction, daily for 3 months) Group II: PFMT (3–8 s PFMT) + Hy- popressive exercises (10 repetitions, daily for 3 months) The knack (3 months) -Levator ani CSA Transperineal Both interven- tion groups had signifi- cantly better improvement in CSA of the levator ani muscle after intervention

Area Study design and population Samples number (mean age) Intervention description Outcome Ultrasound imaging technique

Intervention Control Inter- vention (duration) Control (duration) Bø et al. 2015 [35] Norway RCT (postpartum) 87 (29.5) 88 (30.1) PFMT (3 sets of 8–12 close to maximum contraction, weekly for 4 months) No Exercise prescription -POP stage -Blad- der neck position -POP symptoms -PFM function -PFM strength Transperineal The PFMT program did not improve any of the measured outcomes, and there was no significant difference between groups after intervention Table 1 Details of included studies Page 7 of 12 ShahAli et al. BMC Women's Health (2025) 25:542

Area Study design and population Samples number (mean age) Intervention description Outcome Ultrasound imaging technique

Intervention Control Inter- vention (duration) Control (duration) Ouchi et al. 2019 [36] Japan Clinical trial (not postpartum) 28 (67) - PFMT (10 seconds hold and 10 seconds relax, maximum contraction, 3 sets daily at home and 6 sessions super- vised for 4 months) - -POP stage Transperineal All measured outcomes were improved after the intervention Takaoka al. 2020 [5] Japan Clinical trial (postpartum) 44 (31.1) 45(30.7) PFMT (6 sets of five contrac- tions daily at home, 6-8 seconds hold and relax, last- ing for 4 months), BF Leaflets about postpartum instructions -PFM strength Transperineal The reduction in the LHA was not statistically higher in the intervention group than that in the control group

Area Study design and population Samples number (mean age) Intervention description Outcome Ultrasound imaging technique

Intervention Control Inter- vention (duration) Control (duration) Yin et al. 2022 [28] China RCT (postpartum) 30 (38.55) 30 (39.9) PFMT (7s hold and relax, 10 minutes to 15 minutes, and 3 to 8 times a day, lasting for 8 weeks or more, ES and BF (30 min- utes, 2 times a week for 10 sessions) General postpartum guidance -LHA -PFM strength -PFM thickness Transvaginal The interven- tion group had signifi- cantly better improvement in all the measured out- comes after intervention Zhao et al. 2024 [27] China Clinical trial (postpartum) 60 (31.02) - PFMT (6s hold and 10-20s rest, 10 to 15 repetitions, 3 times a day for 5 weeks), ES and BF (2 times a week for 5 weeks) - -POP stage -PFM strength and activity -PFM sensation -LHA -Blad- der neck position Transperineal All measured outcomes were improved after the intervention BF biofeedback, CSA cross-sectional area, ES electrical stimulation, NR no report, LHA levator hiatus area, PFM pelvic floor muscle, PFMT pelvic floor muscle training, POP pelvic organ prolapse, RCT randomized controlled trial Table 1 (continued) Page 8 of 12 ShahAli et al. BMC Women's Health (2025) 25:542 PFM strength Five studies assessed the effects of PFMT on PFM strength using various outcome measures, including a vaginal balloon catheter [ 25, 35], manometer [ 36], the Modified Oxford Scale [ 27], and, in one study, biofeed - back signal data [28]. The results of the RCTs demonstrated that partici - pants in the PFMT group exhibited significantly greater improvements in PFM strength and activity, as measured by any form of EMG, compared to the control group [ 25, 28, 35]. Additionally, findings from clinical trials demonstrated that PFM strength improved following the PFMT pro - gram compared to baseline measurements [ 27, 36]. A meta-analysis was not performed due to the absence of essential data and the heterogeneity of outcome mea - surement methods across studies. Fig. 2 ( a) Risk of bias summary about each risk of bias domain for each included study separately. ( b) The overall risk of bias graph for included studies Items: (1) Eligibility criteria were specified, (2) Subjects were randomly allocated to groups (in a crossover study, subjects were randomly allocated an order in which treatments were received), (3) Allocation was concealed, (4) The groups were similar at baseline regarding the most important prognostic indica- tors, (5) There was blinding of all subjects, (6) There was blinding of all therapists who administered the therapy, (7) There was blinding of all assessors who measured at least one key outcome, (8) Measures of at least one key outcome were obtained from > 85% of the subjects initially allocated to groups, (9) All subjects for whom outcome measures were available received the treatment or control condition as allocated or, where this was not the case, data for at least one key outcome were analyzed by intention to treat, (10) The results of between-group statistical comparisons are reported for at least one key outcome, 11. The study provides both point measures and measures of variability for at least one key outcome Page 9 of 12 ShahAli et al. BMC Women's Health (2025) 25:542

This systematic review and meta-analysis evaluated the effects of PFMT on PFM morphometry in women with POP . The results indicated that PFMT may improve PFM morphometric parameters, POP stage, and muscle strength, particularly among women with stage I–III POP . To our knowledge, this is the first meta-analysis specifically investigating the effects of PFMT on PFM morphometry in this population. This systematic review and meta-analysis provides evidence supporting the efficacy of PFMT in reducing the LHA both at rest and during the Valsalva maneu - ver. These findings suggest that PFMT elicits measur - able morphological adaptations in the LHA, potentially Fig. 5 Forest plot for the bladder neck position Fig. 4 Forest plot for the levator hiatus area during the Valsalva maneuver Fig. 3 Forest plot for the levator hiatus area during the rest position Page 10 of 12 ShahAli et al. BMC Women's Health (2025) 25:542 indicative of PFM hypertrophy or architectural remodel - ing in response to PFMT, particularly among postpartum populations. These results align with a previous system - atic review reporting favorable morphological changes following PFMT in women with stress urinary inconti - nence and POP [ 17]. Collectively, these data suggest that PFMT may contribute to measurable reductions in LHA, potentially underscoring its clinical relevance in POP rehabilitation. In addition, the findings suggest that PFMT may posi - tively influence bladder neck position in women with POP , particularly those classified as stages I to III. This potentially supports the notion that PFMT could con - tribute to improvements in measurable morphological parameters, aligning with a previous report [ 17]. Mor - phological changes, such as reduced LHA and improved bladder neck position, may address core pathophysiologi- cal mechanisms underlying POP [38]. While PFMT resulted in statistically significant changes in PFM morphometry, the clinical significance of these alterations is unclear. For example, the small elevation in bladder neck position observed in the present systematic review and meta-analysis may reflect inherent ultrasound imaging measurement error, such as variability in probe placement and operator technique [ 39], rather than a true morphological improvement. Moreover, although minimal clinically important differences (MCIDs) have been established for patient-reported outcomes in PFM disorders [ 40], MCIDs for morphometric parameters remain undefined, which may limit clinical interpreta - tion. The predominance of women with POP stages I–III restricts generalizability to more advanced cases. More - over, heterogeneity in PFMT protocols, imaging meth - ods, and supervision intensity, along with the limited number and variable quality of included studies, weakens the strength of evidence. Further high-quality RCTs with standardized interventions and long-term follow-up are needed to confirm these findings and determine optimal training parameters. Evidence on the improvement of the POP stage follow - ing PFMT remains inconsistent. Most RCTs reported significant improvements [25, 27, 36], except one involv - ing group-based PFMT without adjunct modalities [ 35]. Programs incorporating supervision and additional tech - niques, such as biofeedback or electrical stimulation, appeared more effective in improving POP . Similarly, pre- vious systematic reviews have suggested that PFMT may improve the POP stage [ 12, 13], supporting its potential as a conservative first-line therapy. The present findings suggest that PFMT may enhance PFM strength, which in turn could contribute to improvements in the POP stage [ 18]. Most included studies consistently reported significant gains in PFM strength following supervised PFMT [ 25, 27, 28, 35, 36], supporting its role in reinforcing pelvic structural sup - port [ 41]. Intensive, individualized programs, as shown by Hagen et al., were also associated with reduced need for surgical intervention [ 42]. Overall, these findings indicate that PFMT could serve as a first-line conserva - tive approach for POP , although further high-quality RCTs are required to confirm its efficacy and inform clin- ical practice. This systematic review and meta-analysis has some lim- itations. First, considerable heterogeneity across studies, arising from differences in PFMT protocols (e.g., dura - tion, intensity, supervision, use of adjunct modalities) and imaging methods, may have affected pooled esti - mates. Second, most trials lacked long-term follow-up, limiting insights into the sustainability of PFMT effects. Finally, the small number of high-quality RCTs and the absence of participant and therapist blinding increase the risk of bias.

This systematic review and meta-analysis suggest that PFMT may improve PFM morphology, POP stage, and muscle strength among women with POP , particularly in stages I to III. Although evidence indicates possible morphological improvements, such as reductions in LHA and improved bladder neck position, the limited number and variable quality of included studies warrant cautious interpretation. The findings support the potential value of supervised PFMT as a conservative management option for POP; however, the heterogeneity of intervention pro - tocols highlights the need for further high-quality RCTs to confirm these results, establish their long-term clinical relevance, and identify the patient subgroups most likely to benefit. Abbreviations CI Confidence Intervals CINAHL Cumulative Index to Nursing and Allied Health Literature LHA Levator Hiatus Area MCIDs Minimal Clinically Important Differences MD Mean Difference MRI Magnetic Resonance Imaging PEDro Physiotherapy Evidence Database PFM Pelvic Floor Muscle PFMT Pelvic Floor Muscle Training POP Pelvic Organ Prolapse POP-Q Pelvic Organ Prolapse Quantification System PRISMA Preferred Reporting Items for Systematic Reviews and Meta-Analyses RCTs Randomized Controlled Trials REML Random-Effects Model with the restricted maximum Likelihood Supplementary Information The online version contains supplementary material available at h t t p s : / / d o i . o r g / 1 0 . 1 1 8 6 / s 1 2 9 0 5 - 0 2 5 - 0 4 0 9 5 - 2. Supplementary Material 1. Page 11 of 12 ShahAli et al. BMC Women's Health (2025) 25:542

Not applicable. Authors’ contributions SS: Concept development, literature searches, drafting, and revising the manuscript. KB: Contributed to study design, manuscript preparation, and editing. AH: Contributed to study design, conducted statistical analyses, and assisted in manuscript preparation. HH: Contributed to study design and performed data extraction. GK: Contributed to study design, performed data extraction, drafting, and revising the manuscript. All authors reviewed and approved the final version of the manuscript. Funding Not applicable. Data availability The datasets used and/or analysed during the current study are available from the corresponding author on reasonable request. Declarations Ethics approval and consent to participate Not applicable. Consent for publication Not applicable. Competing interests The authors declare no competing interests. Author details 1Iranian Center of Excellence in Physiotherapy, Rehabilitation Research Center, Department of Physiotherapy, School of Rehabilitation Sciences, Iran University of Medical Sciences, Tehran, Iran 2Department of Sports Medicine, Norwegian School of Sport Sciences, Oslo, Norway 3Department of Physiology, School of Medicine, Iran University of Medical Sciences, Tehran, Iran Received: 1 September 2025 / Accepted: 10 October 2025

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