The pelvic floor is a complex musculofascial structure that provides support to the pelvic organs and contributes to urinary and faecal continence, sexual function, intra-abdominal pressure regulation and lumbopelvic stability. Adequate strength, endurance and coordination of the pelvic floor muscles are therefore essential for maintaining normal pelvic health. Weakness or injury of these muscles may result in urinary incontinence, faecal incontinence, pelvic organ prolapse, sexual dysfunction and impaired quality of life. Pelvic floor muscle function can be evaluated clinically through vaginal digital palpation, the Modified Oxford Scale and the PERFECT assessment scheme, or objectively using pressure-based instruments such as vaginal perineometers. Standardized terminology and assessment procedures are essential for achieving reliable and comparable measurements [1]. Pregnancy and childbirth are considered major determinants of pelvic floor dysfunction. During pregnancy, hormonal alterations, increased uterine weight and elevated intra-abdominal pressure place progressive mechanical stress on the pelvic floor. Vaginal childbirth may further affect pelvic floor integrity through stretching, compression or injury to the levator ani muscles, connective tissues and pudendal nerves. These changes may reduce muscle strength and endurance even when women do not report overt pelvic floor symptoms. Repeated pregnancies and deliveries may have cumulative effects, making multiparous women potentially more susceptible to pelvic floor muscle weakness than nulliparous women [2]. Previous studies have demonstrated an inverse association between parity and pelvic floor muscle strength. Özdemir et al. observed that pelvic floor muscle strength declined with increasing number of deliveries, with the greatest reduction occurring among women with high parity [3]. Afshari et al. reported that nulliparous women had higher pelvic floor muscle strength than women who had experienced childbirth, although differences according to mode of delivery were not consistently significant [4]. Similarly, Pandey et al. found significantly higher pelvic floor muscle strength among nulliparous women than among multiparous women [5]. Nevertheless, pelvic floor strength may also be influenced by age, body mass index, physical activity, menopausal status, mode of delivery, instrumental delivery, perineal trauma, neonatal birth weight and previous pelvic floor muscle training. Early identification of reduced pelvic floor muscle strength could facilitate timely counselling, preventive exercises and referral for pelvic floor rehabilitation before clinically significant dysfunction develops. However, evidence comparing objectively measured muscle strength among multiparous and nulliparous women remains limited in many clinical settings. Therefore, the present study was undertaken to compare pelvic floor muscle strength in multiparous and nulliparous women and to examine selected factors associated with reduced strength. AIM To compare pelvic floor muscle strength between multiparous and nulliparous women. OBJECTIVES 1. To assess pelvic floor muscle strength among multiparous women using standardized clinical and perineometric measurements. 2. To assess and compare pelvic floor muscle strength among nulliparous women using the same assessment methods. 3. To determine the association of pelvic floor muscle strength with selected sociodemographic, anthropometric and obstetric factors.

The study participants were recruited from women attending the outpatient departments of Obstetrics and Gynaecology and Physiotherapy. Eligible women were enrolled after the purpose and procedures of the study had been explained to them. Sociodemographic, anthropometric, clinical and obstetric information was obtained through interviews, medical records and physical examination. Participants were classified into multiparous and nulliparous groups according to their obstetric histories. Study Design The study was a hospital-based comparative cross-sectional study. Pelvic floor muscle strength was assessed at a single study visit and compared between multiparous and nulliparous women. Study Location The study was conducted in the Departments of Obstetrics and Gynaecology and Physiotherapy. Participant interviews and physical examinations were undertaken in a private examination room to maintain confidentiality and comfort. Study Duration The study was conducted over 12 months, including participant recruitment, data collection, analysis and report preparation. Sample Size A total of 160 women were included. Participants were divided equally into two groups: • Group A: 80 multiparous women who had delivered two or more viable pregnancies. • Group B: 80 nulliparous women who had never completed a pregnancy beyond the age of viability. The sample size was predetermined as 160 participants to provide adequate representation of both groups. Eligible participants were recruited consecutively until 80 women had been enrolled in each group. Inclusion Criteria Multiparous group • Women aged 20-45 years. • Women with a history of two or more deliveries beyond the age of viability. • Women whose last delivery had occurred at least six months before assessment. • Women able to understand and perform a voluntary pelvic floor muscle contraction. • Women who provided written informed consent. Nulliparous group • Women aged 20-45 years. • Women who had never delivered a viable fetus. • Non-pregnant women. • Women able to understand and perform a voluntary pelvic floor muscle contraction. • Women who provided written informed consent. Exclusion Criteria • Current pregnancy or a delivery within the preceding six months. • Previous pelvic, gynaecological or continence surgery. • Diagnosed pelvic organ prolapse of stage II or higher. • Active urinary tract, vaginal or pelvic infection. • Current menstruation or unexplained vaginal bleeding at assessment. • Congenital pelvic or lower urinary tract abnormalities. • Neurological or neuromuscular disease affecting pelvic floor function. • Severe pelvic pain or inability to tolerate vaginal examination. • Current pelvic malignancy or history of pelvic radiotherapy. • Women receiving supervised pelvic floor rehabilitation at recruitment. • Inability or unwillingness to provide informed consent. Procedure and Methodology Ethical approval was obtained from the Institutional Ethics Committee before recruitment began. Written informed consent was obtained from every participant. Each woman was assigned a unique study identification number. A detailed history was recorded, including age, education, occupation, physical activity, bowel habits, urinary symptoms, previous pelvic floor muscle training and relevant medical history. In multiparous women, obstetric information included parity, mode and number of deliveries, instrumental delivery, episiotomy, perineal tear, interval since the last delivery and highest neonatal birth weight. Height and weight were measured using standardized equipment, and body mass index was calculated as weight in kilograms divided by height in metres squared. The assessment was performed with the participant in the crook-lying position, with the hips and knees flexed and slightly abducted. The examiner first explained pelvic floor contraction as an inward squeezing and upward lifting action around the vagina and anus without contracting the abdominal, gluteal or thigh muscles. Correct contraction was confirmed through observation and vaginal digital palpation. Pelvic floor muscle power was graded using the Modified Oxford Scale: • Grade 0: no contraction; • Grade 1: flicker or trace contraction; • Grade 2: weak contraction; • Grade 3: moderate contraction with some lift; • Grade 4: good contraction with lift against resistance; • Grade 5: strong contraction with firm lift against resistance. The PERFECT scheme was additionally used to record power, endurance, number of sustained repetitions and number of fast contractions. Endurance was recorded as the number of seconds for which a maximal contraction could be maintained, up to 10 seconds. Objective strength was measured using a calibrated vaginal perineometer. The probe was covered with a sterile disposable sheath, lubricated with a small quantity of water-soluble gel and inserted according to the manufacturer’s instructions. After the baseline pressure had stabilized, the participant was instructed to perform a maximal pelvic floor contraction without holding her breath or performing a Valsalva manoeuvre. Three maximal contractions were recorded, with a rest interval of 30-60 seconds between attempts. The highest valid pressure and the mean of the three measurements were documented in centimetres of water or millimetres of mercury, depending on the device. Measurements associated with visible abdominal straining, breath-holding or probe displacement were rejected and repeated after adequate rest. All assessments were performed by the same trained examiner whenever feasible to minimize interobserver variation. Sample Processing No blood, urine, tissue or other biological specimen was collected; therefore, laboratory sample processing was not applicable. Perineometric measurements were treated as physiological data. The vaginal probe was covered with a new disposable sheath for each participant and disinfected according to the manufacturer’s infection-control instructions. Recorded measurements were checked immediately for artefacts, incomplete contractions and data-entry errors. Data Collection Data were collected using a predesigned, pretested case-record form. The form contained sections covering sociodemographic characteristics, anthropometric measurements, medical history, urinary and bowel symptoms, physical activity, obstetric history, Modified Oxford Scale grade, PERFECT assessment parameters and perineometric pressure. The data-collection instrument was pilot-tested among a small group of women who were not included in the final analysis. Completed forms were reviewed daily for completeness and consistency. Data were coded, anonymized and entered into an electronic spreadsheet, and a proportion of entries was cross-checked against the original forms. Statistical Methods Data were analysed using SPSS 28.0. Continuous variables were summarized as mean and standard deviation when normally distributed and as median and interquartile range when non-normally distributed. Categorical variables were expressed as frequencies and percentages. The independent-samples t test was used to compare normally distributed pelvic floor strength measurements between the two groups. The Mann-Whitney U test was used for non-normally distributed or ordinal measurements. Modified Oxford Scale grades and other categorical variables were compared using the chi-square test or Fisher’s exact test, as appropriate. Mean or median differences, odds ratios and corresponding 95% confidence intervals were reported. Pearson’s or Spearman’s correlation coefficient was used to assess relationships between pelvic floor strength and continuous variables. Multiple linear regression was used to identify independent predictors of perineometric strength after adjustment for potential confounders such as age, body mass index, parity, mode of delivery, perineal trauma and previous pelvic floor muscle training. Statistical significance was set at a two-sided P value of <0.05.

Table 1: Comparison of pelvic floor muscle strength between multiparous and nulliparous women (N=160) Pelvic floor assessment Multiparous (n=80), n (%) or Mean (SD) Nulliparous (n=80), n (%) or Mean (SD) Effect estimate (95% CI) Test of significance P value Modified Oxford Scale score 2.68 (0.88) 3.61 (0.72) MD=−0.93 (−1.18 to −0.68) t=−7.31 <0.001* Perineometric pressure, cmH₂O 27.4 (8.7) 39.8 (9.2) MD=−12.40 (−15.20 to −9.60) t=−8.76 <0.001* Endurance, seconds 5.4 (1.9) 7.1 (1.8) MD=−1.70 (−2.28 to −1.12) t=−5.81 <0.001* Sustained contractions completed 4.8 (1.8) 6.5 (1.7) MD=−1.70 (−2.25 to −1.15) t=−6.14 <0.001* Fast contractions completed 6.2 (2.4) 8.1 (2.2) MD=−1.90 (−2.62 to −1.18) t=−5.21 <0.001* Reduced muscle strength, MOS ≤2 37 (46.3) 11 (13.8) OR=5.39 (2.47-11.77) χ²=20.04 <0.001* Moderate strength, MOS grade 3 29 (36.3) 31 (38.8) OR=0.90 (0.48-1.71) χ²=0.11 0.743 Good-to-strong strength, MOS grades 4-5 14 (17.5) 38 (47.5) OR=0.23 (0.11-0.48) χ²=16.44 <0.001* Correct isolated pelvic floor contraction 59 (73.8) 73 (91.3) OR=0.27 (0.11-0.67) χ²=8.44 0.004* Accessory muscle recruitment 32 (40.0) 13 (16.3) OR=3.44 (1.63-7.26) χ²=11.13 0.001* Independent-samples t-test was used for continuous variables and chi-square test for categorical variables. MD: mean difference, calculated as multiparous minus nulliparous; OR: odds ratio; MOS: Modified Oxford Scale. *Statistically significant at P<0.05. Table 1 compares pelvic floor muscle strength between 80 multiparous and 80 nulliparous women. Multiparous women had a significantly lower mean Modified Oxford Scale score than nulliparous women (2.68±0.88 versus 3.61±0.72), with a mean difference of −0.93 (95% CI: −1.18 to −0.68; t=−7.31; P<0.001). Similarly, mean perineometric pressure was significantly lower among multiparous women (27.4±8.7 cmH₂O) than among nulliparous women (39.8±9.2 cmH₂O), with a mean difference of −12.40 cmH₂O (95% CI: −15.20 to −9.60; P<0.001). Multiparous women also demonstrated significantly lower endurance (5.4±1.9 versus 7.1±1.8 seconds), fewer sustained contractions (4.8±1.8 versus 6.5±1.7) and fewer fast contractions (6.2±2.4 versus 8.1±2.2); all differences were statistically significant at P<0.001. Reduced muscle strength, defined as an MOS grade ≤2, was observed in 46.3% of multiparous women compared with 13.8% of nulliparous women. Multiparous women had 5.39 times higher odds of reduced muscle strength (95% CI: 2.47-11.77; P<0.001). In contrast, good-to-strong muscle strength was less frequent among multiparous women than nulliparous women (17.5% versus 47.5%; OR=0.23, 95% CI: 0.11-0.48; P<0.001). There was no significant difference in the proportion with moderate strength (36.3% versus 38.8%; P=0.743). Correct isolated pelvic floor contraction was less common among multiparous women (73.8% versus 91.3%; P=0.004), whereas accessory muscle recruitment was more common (40.0% versus 16.3%; OR=3.44, 95% CI: 1.63-7.26; P=0.001). Table 2: Clinical and perineometric assessment of pelvic floor muscle strength among multiparous women according to parity (n=80) Assessment Parity 2 (n=43), n (%) or Mean (SD) Parity ≥3 (n=37), n (%) or Mean (SD) Effect estimate (95% CI) Test of significance P value Modified Oxford Scale score 2.98 (0.83) 2.32 (0.82) MD=0.66 (0.29-1.03) t=3.57 <0.001* Perineometric pressure, cmH₂O 30.4 (8.2) 23.9 (8.0) MD=6.50 (2.90-10.10) t=3.58 <0.001* Endurance, seconds 6.0 (1.8) 4.7 (1.8) MD=1.30 (0.50-2.10) t=3.22 0.002* Sustained contractions completed 5.4 (1.7) 4.1 (1.7) MD=1.30 (0.54-2.06) t=3.41 0.001* Fast contractions completed 6.9 (2.3) 5.4 (2.3) MD=1.50 (0.47-2.53) t=2.91 0.005* Reduced muscle strength, MOS ≤2 13 (30.2) 24 (64.9) OR=0.23 (0.09-0.58) χ²=9.59 0.002* Moderate strength, MOS grade 3 19 (44.2) 10 (27.0) OR=2.14 (0.84-5.43) χ²=2.53 0.112 Good-to-strong strength, MOS grades 4-5 11 (25.6) 3 (8.1) OR=3.90 (1.00-15.26) Fisher’s exact 0.046* Correct isolated contraction 36 (83.7) 23 (62.2) OR=3.13 (1.10-8.88) χ²=4.78 0.029* Accessory muscle recruitment 12 (27.9) 20 (54.1) OR=0.33 (0.13-0.84) χ²=5.68 0.017* Involuntary contraction during cough 28 (65.1) 17 (45.9) OR=2.20 (0.89-5.43) χ²=2.97 0.085 MD was calculated as parity 2 minus parity ≥3. MOS: Modified Oxford Scale; OR: odds ratio. *Statistically significant at P<0.05. Table 2 presents pelvic floor muscle assessments among multiparous women according to parity. Women with parity two demonstrated a significantly higher mean MOS score than women with parity three or more (2.98±0.83 versus 2.32±0.82; MD=0.66, 95% CI: 0.29-1.03; P<0.001). Mean perineometric pressure was also significantly higher in women with parity two (30.4±8.2 cmH₂O) than in those with parity three or more (23.9±8.0 cmH₂O), representing a mean difference of 6.50 cmH₂O (95% CI: 2.90-10.10; P<0.001). Women with parity two had greater endurance (6.0±1.8 versus 4.7±1.8 seconds; P=0.002), completed more sustained contractions (5.4±1.7 versus 4.1±1.7; P=0.001) and completed more fast contractions (6.9±2.3 versus 5.4±2.3; P=0.005). Reduced muscle strength was identified in 30.2% of women with parity two and 64.9% of women with parity three or more (OR=0.23, 95% CI: 0.09-0.58; P=0.002). Conversely, good-to-strong muscle strength was more frequent among women with parity two (25.6% versus 8.1%; OR=3.90, 95% CI: 1.00-15.26; P=0.046). Correct isolated contraction was more common in the parity-two group (83.7% versus 62.2%; P=0.029), while accessory muscle recruitment was less common (27.9% versus 54.1%; P=0.017). Although involuntary contraction during coughing was more frequent among women with parity two (65.1% versus 45.9%), the difference did not reach statistical significance (P=0.085). Table 3: Relationship between clinical grading and perineometric measurements among nulliparous women (n=80) Assessment Reduced strength, MOS ≤2 (n=11) Moderate strength, MOS 3 (n=31) Good-to-strong strength, MOS 4-5 (n=38) Effect estimate (95% CI) Test of significance P value Participants, n (%) 11 (13.8) 31 (38.8) 38 (47.5) χ²=14.33† 0.001* Perineometric pressure, cmH₂O 25.8 (5.4) 36.9 (6.2) 45.3 (7.1) Mean difference across extreme groups=19.50 (14.78-24.22) ANOVA F=39.62 <0.001* Endurance, seconds 4.8 (1.3) 6.7 (1.4) 8.1 (1.5) Mean difference=3.30 (2.27-4.33) ANOVA F=25.71 <0.001* Sustained contractions completed 4.1 (1.2) 6.1 (1.4) 7.4 (1.5) Mean difference=3.30 (2.29-4.31) ANOVA F=26.48 <0.001* Fast contractions completed 5.6 (1.8) 7.7 (1.9) 9.1 (2.0) Mean difference=3.50 (2.15-4.85) ANOVA F=14.66 <0.001* Correct isolated contraction, n (%) 7 (63.6) 28 (90.3) 38 (100.0) Fisher’s exact <0.001* Accessory muscle recruitment, n (%) 7 (63.6) 5 (16.1) 1 (2.6) Fisher’s exact <0.001* Involuntary contraction during cough, n (%) 4 (36.4) 21 (67.7) 33 (86.8) χ²=12.13 0.002* †Chi-square goodness-of-fit test assessed whether the three strength categories were equally distributed. The reported mean difference and 95% CI compare MOS ≤2 with MOS grades 4-5. MOS: Modified Oxford Scale; ANOVA: analysis of variance. *Statistically significant at P<0.05.* Among nulliparous women, the Modified Oxford Scale grade showed a strong positive correlation with perineometric pressure: Pearson’s r=0.71 (95% CI: 0.58-0.80), P<0.001. Table 3 demonstrates the relationship between clinical strength grading and objective perineometric measurements among 80 nulliparous women. Of these, 11 (13.8%) had reduced strength, 31 (38.8%) had moderate strength and 38 (47.5%) had good-to-strong strength. The distribution differed significantly across the three categories (χ²=14.33; P=0.001). Mean perineometric pressure increased progressively from 25.8±5.4 cmH₂O in women with reduced strength to 36.9±6.2 cmH₂O in those with moderate strength and 45.3±7.1 cmH₂O in those with good-to-strong strength. The difference between the extreme categories was 19.50 cmH₂O (95% CI: 14.78-24.22), and the overall difference was significant (ANOVA F=39.62; P<0.001). Similar progressive improvements were observed in endurance, sustained contractions and fast contractions across the increasing MOS categories, with all comparisons significant at P<0.001. Correct isolated contraction increased from 63.6% in the reduced-strength group to 90.3% in the moderate group and 100.0% in the good-to-strong group (P<0.001). Conversely, accessory muscle recruitment decreased markedly from 63.6% to 16.1% and 2.6%, respectively (P<0.001). Involuntary contraction during coughing increased from 36.4% in the reduced-strength group to 86.8% in the good-to-strong group (P=0.002). Furthermore, the MOS grade showed a strong positive correlation with perineometric pressure (r=0.71, 95% CI: 0.58-0.80; P<0.001), demonstrating good convergence between clinical grading and objective pressure measurement. Table 4: Factors associated with reduced pelvic floor muscle strength Panel A. Sociodemographic and anthropometric predictors in the total sample (N=160) Factor Reduced strength (n=48), n (%) or Mean (SD) Normal strength (n=112), n (%) or Mean (SD) Unadjusted effect (95% CI) Adjusted OR (95% CI) Test statistic P value Multiparous status 37 (77.1) 43 (38.4) OR=5.39 (2.47-11.77) 4.21 (1.81-9.79) Wald χ²=10.77 0.001* Age ≥35 years 29 (60.4) 37 (33.0) OR=3.09 (1.54-6.20) 2.18 (1.01-4.71) Wald χ²=3.95 0.047* BMI ≥25 kg/m² 31 (64.6) 43 (38.4) OR=2.93 (1.45-5.91) 2.36 (1.09-5.10) Wald χ²=4.73 0.030* Sedentary lifestyle 28 (58.3) 41 (36.6) OR=2.42 (1.21-4.85) 1.94 (0.91-4.15) Wald χ²=2.95 0.086 Chronic constipation 17 (35.4) 18 (16.1) OR=2.86 (1.31-6.26) 2.47 (1.05-5.82) Wald χ²=4.30 0.038* Previous pelvic floor exercises 7 (14.6) 37 (33.0) OR=0.35 (0.14-0.85) 0.39 (0.15-0.99) Wald χ²=3.93 0.047* Panel B. Obstetric predictors among multiparous women (n=80) Obstetric factor Reduced strength (n=37), n (%) Normal strength (n=43), n (%) Unadjusted OR (95% CI) Adjusted OR (95% CI) Test statistic P value Parity ≥3 24 (64.9) 13 (30.2) 4.26 (1.69-10.73) 3.48 (1.26-9.61) Wald χ²=5.77 0.016* Any vaginal delivery 31 (83.8) 24 (55.8) 4.09 (1.42-11.74) 3.31 (1.05-10.39) Wald χ²=4.18 0.041* Instrumental vaginal delivery 13 (35.1) 6 (14.0) 3.34 (1.13-9.87) 2.76 (0.84-9.07) Wald χ²=2.80 0.094 Previous third-/fourth-degree perineal tear 9 (24.3) 3 (7.0) 4.28 (1.08-17.01) 3.89 (0.89-16.95) Wald χ²=3.28 0.070 Highest birth weight ≥3.5 kg 18 (48.6) 9 (20.9) 3.58 (1.37-9.38) 3.12 (1.10-8.82) Wald χ²=4.57 0.033* Interval since last delivery ≥5 years 23 (62.2) 18 (41.9) 2.28 (0.93-5.58) 1.71 (0.64-4.57) Wald χ²=1.14 Table 4 examines factors associated with reduced pelvic floor muscle strength. In the total sample, multiparous status was substantially more frequent among women with reduced strength than among those with normal strength (77.1% versus 38.4%). After adjustment for other factors, multiparous women had 4.21 times higher odds of reduced pelvic floor muscle strength (95% CI: 1.81-9.79; P=0.001). Age ≥35 years (aOR=2.18, 95% CI: 1.01-4.71; P=0.047), BMI ≥25 kg/m² (aOR=2.36, 95% CI: 1.09-5.10; P=0.030) and chronic constipation (aOR=2.47, 95% CI: 1.05-5.82; P=0.038) were also independently associated with increased odds of reduced muscle strength. Previous pelvic floor exercise was independently associated with lower odds of reduced strength (aOR=0.39, 95% CI: 0.15-0.99; P=0.047). Although a sedentary lifestyle showed an increased unadjusted association, it was not statistically significant after adjustment (aOR=1.94, 95% CI: 0.91-4.15; P=0.086). Among multiparous women, parity of three or more remained independently associated with reduced muscle strength (aOR=3.48, 95% CI: 1.26-9.61; P=0.016). Any history of vaginal delivery was associated with 3.31 times higher adjusted odds of reduced strength (95% CI: 1.05-10.39; P=0.041). Delivery of an infant weighing ≥3.5 kg was also an independent factor (aOR=3.12, 95% CI: 1.10-8.82; P=0.033). Instrumental vaginal delivery (aOR=2.76; P=0.094), previous third- or fourth-degree perineal tear (aOR=3.89; P=0.070) and an interval of ≥5 years since the last delivery (aOR=1.71; P=0.286) showed increased adjusted odds but were not statistically significant. The wide confidence intervals for some obstetric factors suggest limited precision, probably because of the relatively small number of women within these subgroups.

Table 1: Comparison between multiparous and nulliparous women The present study demonstrated consistently lower pelvic floor muscle function among multiparous women than nulliparous women. Multiparous participants had a significantly lower mean Modified Oxford Scale (MOS) score (2.68±0.88 versus 3.61±0.72), perineometric pressure (27.4±8.7 versus 39.8±9.2 cmH₂O), endurance, and numbers of sustained and fast contractions, with all comparisons yielding P<0.001. Reduced muscle strength was present in 46.3% of multiparous women compared with 13.8% of nulliparous women, giving multiparous women 5.39 times higher odds of reduced strength. These results closely agree with Afshari et al. (2017)[1], who studied 341 women and found that nulliparous women had the highest mean perineometric strength (55.62±15.86 cmH₂O), whereas women with vaginal delivery and episiotomy had the lowest strength (32.71±14.00 cmH₂O). Pandey et al. (2020)[2] similarly reported mean perineometric pressures of 40.04 cmH₂O in nulliparous women and 37.69 cmH₂O in parous women, with significantly higher pelvic floor muscle strength in the nulliparous group. Differences in absolute pressure values between studies may reflect variations in the perineometer, probe dimensions, participant position, contraction instructions and time since childbirth. The lower endurance and fewer sustained and fast contractions among multiparous women suggest that parity affected not only maximal force generation but also functional performance. Özdemir et al. (2015)[3] observed progressively poorer pelvic floor muscle strength among women with increasing numbers of deliveries, supporting a cumulative influence of pregnancy and childbirth. Bertacini et al. (2020)[4] also found that long-term pelvic floor function differed according to obstetric history, although they noted that the first childbirth may produce much of the initial functional alteration. The higher prevalence of accessory muscle recruitment in multiparous women in the present study (40.0% versus 16.3%) may indicate impaired neuromuscular coordination or compensation by the abdominal, gluteal or adductor muscles. Conversely, correct isolated contraction was more frequent in nulliparous women (91.3% versus 73.8%). These findings support the need to assess contraction quality and coordination in addition to maximal pressure. Table 2: Pelvic floor muscle function according to parity among multiparous women Among multiparous women, those with parity three or more had lower MOS scores, perineometric pressure, endurance and contraction performance than those with parity two. Mean perineometric pressure declined from 30.4±8.2 cmH₂O in women with parity two to 23.9±8.0 cmH₂O in women with parity three or more. Reduced strength was present in 64.9% of the higher-parity group compared with 30.2% of the parity-two group. Correct isolated contraction was also less common, while accessory muscle recruitment was more frequent in women with parity three or more. These observations are comparable to Özdemir et al. (2015)[3], who found that women with one to three deliveries had greater muscle strength than women with four to six or more than six deliveries. Repeated pregnancy and childbirth may impose cumulative mechanical loading, muscle stretching, connective-tissue remodelling and pudendal nerve compression, which could explain the poorer strength and endurance observed with higher parity. The present results are also consistent with Gümüşsoy et al. (2020)[5], who evaluated 258 reproductive-aged women and concluded that parity had a dominant influence on pelvic floor muscle weakness and was more strongly associated with strength than with endurance. Bertacini et al. (2020)[4], however, did not identify a simple progressive deterioration across all parity categories, indicating that the relationship may be influenced by age, delivery mode, time since delivery, physical activity and recovery. Likewise, Fang et al. (2020)[6], in a large retrospective study of 21,302 postpartum women, unexpectedly found a positive association of parity up to three with electromyographic contraction amplitude. The authors suggested that postpartum adaptation and muscular recovery might partly explain this finding. Differences from the present study could also be attributable to Fang et al.’s early-postpartum population and use of surface electromyography rather than perineometry and digital palpation. Thus, although the present results support a cumulative effect of parity, the relationship may vary according to the population, postpartum interval and assessment technique. The proportion demonstrating involuntary contraction during coughing was lower in women with parity three or more, but the difference was not statistically significant (45.9% versus 65.1%; P=0.085). This suggests a possible decline in reflexive pelvic floor response with increasing parity, although the study may have had insufficient power for this comparison. The non-significant result should therefore not be interpreted as evidence of equivalence. Table 3: Relationship between MOS grading and perineometry among nulliparous women Among nulliparous women, objective pelvic floor measurements increased progressively with clinical MOS grade. Mean perineometric pressure rose from 25.8±5.4 cmH₂O in women with MOS ≤2 to 36.9±6.2 cmH₂O in those with MOS grade 3 and 45.3±7.1 cmH₂O in those with grades 4-5. Comparable stepwise increases were observed in endurance and sustained and fast contractions. The MOS grade had a strong positive correlation with perineometric pressure (r=0.71, 95% CI: 0.58-0.80; P<0.001). This supports the convergent validity of clinical palpation and objective pressure measurement. Lançanova et al. (2020)[7], in a systematic review and meta-analysis, similarly found a high positive correlation between perineometry and the MOS when both assessments were performed using standardized procedures. Gümüşsoy et al. (2020)[5] also reported positive agreement between MOS grading and perineometric measurements among reproductive-aged women. Sartori et al. (2015)[8] showed that standardized transvaginal digital palpation could provide clinically useful and reasonably reliable evaluation of pelvic floor strength, although reliability varied according to examiner and assessment site. These findings reinforce the importance of standardized instructions, examiner training, participant positioning and avoidance of the Valsalva manoeuvre. Correct isolated contraction increased from 63.6% among women with reduced strength to 100% among those with good-to-strong strength, whereas accessory muscle recruitment decreased from 63.6% to 2.6%. This demonstrates that higher strength was accompanied by better neuromuscular control. Nevertheless, digital palpation and perineometry assess related but not identical properties: digital examination evaluates lift, squeeze and contraction quality, whereas perineometry quantifies intravaginal pressure, which may be influenced by probe position and intra-abdominal pressure. Frawley et al. (2020)[9] therefore recommended standardized terminology and comprehensive reporting of strength, endurance, coordination, relaxation and involuntary responses rather than reliance on a single measurement. Table 4: Factors associated with reduced pelvic floor muscle strength Multivariable analysis showed that multiparous status was the strongest independent predictor of reduced strength (aOR=4.21, 95% CI: 1.81-9.79). Age ≥35 years, BMI ≥25 kg/m² and chronic constipation were also independently associated with reduced strength. These findings are broadly consistent with Gümüşsoy et al. (2020)[5], who identified age, parity and selected sociodemographic and obstetric characteristics as determinants of pelvic floor muscle strength. Sartori et al. (2015)[8] also observed age-related variation in pelvic floor strength among healthy multiparous women. Ageing may reduce skeletal muscle mass, neuromuscular efficiency and connective-tissue elasticity. Increased BMI and chronic constipation may expose the pelvic floor to repeated or sustained elevations in intra-abdominal pressure, although the cross-sectional design cannot establish causality. Fang et al. (2020)[6] similarly found that older age was negatively related to rapid, tonic and endurance contractions. Their association with BMI differed from the present study: BMI showed a positive relationship with electromyographic amplitude in their early-postpartum cohort. This inconsistency may reflect differences between muscle electrical activity and pressure-based strength, as well as differences in postpartum stage, body composition and residual confounding. Consequently, BMI findings should be interpreted within the measurement and population context. Previous pelvic floor muscle exercise was independently associated with 61% lower odds of reduced strength (aOR=0.39, 95% CI: 0.15-0.99). This finding is biologically plausible because correctly performed training improves motor recruitment, strength and endurance. Woodley et al. (2020)[10] concluded that structured antenatal pelvic floor muscle training probably reduces the risk of urinary incontinence in late pregnancy and the early postpartum period, although evidence regarding treatment effects in all postpartum women was less certain. Because exercise history in the present study was self-reported, reverse causation and recall bias remain possible. Among multiparous women, parity ≥3, any vaginal delivery and neonatal birth weight ≥3.5 kg remained independently associated with reduced muscle strength. Fang et al. (2020)[6] likewise found that increasing neonatal weight, vaginal delivery, episiotomy and forceps delivery were associated with poorer postpartum pelvic floor contraction parameters. Afshari et al. (2017)[1] found the lowest strength among women who had undergone vaginal delivery with episiotomy, although differences between vaginal delivery without episiotomy and caesarean delivery were not significant. Instrumental delivery and severe perineal tears showed elevated adjusted odds in the present study but did not reach statistical significance. Their wide confidence intervals indicate limited precision, probably because relatively few participants had these exposures. Overall, the findings support an association of repeated childbirth and obstetric mechanical loading with reduced pelvic floor muscle strength, while also emphasizing that age, BMI, bowel habits and exercise contribute to pelvic floor function.

Multiparous women demonstrated significantly poorer pelvic floor muscle strength than nulliparous women, as reflected by lower Modified Oxford Scale scores, perineometric pressure, endurance, and sustained and fast contraction performance. Reduced pelvic floor muscle strength was considerably more frequent among multiparous women, who also showed less accurate isolated contraction and greater accessory muscle recruitment. Among multiparous participants, parity of three or more was associated with further deterioration in clinical and perineometric measurements. Multiparity, older age, elevated body mass index, chronic constipation, vaginal delivery and higher neonatal birth weight were independently associated with reduced strength, whereas previous pelvic floor muscle exercise appeared protective. The strong positive correlation between Modified Oxford Scale grading and perineometric pressure supported the combined use of clinical palpation and perineometry for assessment. These findings highlight the importance of routine pelvic floor evaluation, education and appropriately supervised muscle training, particularly for women with multiple childbirths or other associated risk factors.

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