Pelvic organ prolapse (POP) is increasingly prevalent due to an aging population, affecting up to 50% of parous women, the majority of whom are over the age of 60 years [1, 2]. Epidemiological data indicate that the incidence of POP in women over 60 years of age in China reaches 73.9% [3]. Clinical manifestations of POP include pelvic pain and descent of the vaginal wall or apex, often accompanied by urinary, sexual, and anorectal dysfunction [4]. Although POP is not life-threatening, its prevalence increases markedly with advancing age [5, 6].

Currently, the pathogenesis of POP remains unclear, with its etiology and associated risk factors still under debate [7]. It is generally believed that POP results from chronic damage to the pelvic floor support structures, influenced by risk factors such as pregnancy, childbirth, prolonged elevated intra-abdominal pressure, and estrogen deficiency [8]. POP significantly impacts the quality of life for middle-aged and older women, making the identification of key risk factors essential for raising awareness and enabling early prevention. However, large-scale studies on the prevalence and risk factors for POP in Chinese women are scarce. One study involving 2668 women identified aging, menopause, number of pregnancies, childbirth, body mass index (BMI), and mode of delivery as associated factors of POP and urinary incontinence [9]. However, its smaller sample size may have underestimated the true prevalence and severity of the condition.

The present study aimed to analyze the distribution of POP across various severity stages, identify its risk factors, and explore its underlying pathogenesis in a large cohort of Chinese women. The findings are expected to promote self-examination and early prevention among women, while also assisting clinicians in improving preoperative assessments and advancing individualized, precision-based treatment strategies.

POP is a chronic condition that predominantly affects middle-aged and elderly postmenopausal women, primarily due to the weakening of pelvic floor tissues [11]. With the aging global population and an increasing emphasis on quality of life, resulting in a growing number of patients seeking diagnosis and treatment. Our study shows that grade II prolapse is most commonly observed in the anterior vaginal wall, whereas grade I prolapse is more prevalent in the posterior vaginal wall. Factors such as childbearing age, parity, BMI, and mode of delivery are associated with POP, with advanced maternal age (AMA) identified as independent risk factors. Vaginal delivery significantly increases the risk of vaginal prolapse, while occupations involving prolonged physical labor are associated with an increased risk of posterior vaginal wall prolapse.

The International Federation of Gynecology and Obstetrics and the American College of Obstetricians and Gynecologists defined AMA as 35 years or older at the estimated date of delivery [12, 13]. Our findings indicate a correlation between AMA and an elevated risk of POP, with vaginal deliveries being associated with a 3.85-fold higher likelihood of prolapse compared to cesarean sections. Supporting this, Wang et al. [14] reported a 6% increase in prolapse rates for each year of delay in first childbirth, with rates more than tripling when comparing first-time births at ages 20 and 40. This increase is attributed to a higher risk of severe pelvic floor injuries, including levator ani avulsion and severe perineal lacerations, which are more commonly associated with older maternal age [15, 16]. Consequently, women of AMA may be more susceptible to POP, aligning with National Institute for Health and Care Excellence (NICE) guidelines, which identify maternal age over 30 years at childbirth as a risk factor for pelvic floor dysfunction [17].

Our study further identified prolonged physical labor as a significant risk factor for posterior vaginal wall prolapse. From an abdominal-pelvic biomechanics perspective, maintaining a stable balance of dynamic forces within the abdominopelvic cavity is crucial for maintaining normal function. Prolonged physical labor elevates intra-abdominal pressure, disrupting this balance [18] and stressing pelvic floor structures. This stress leads to muscle and connective tissue fatigue and relaxation, thereby heightening the risk of prolapse. This may help explain the higher prevalence of POP among women in low-income environments. A study from rural areas indicates that insufficient postpartum rest and heavy lifting during daily chores are major contributors to prolapse [19]. Lifting heavy objects for five or more hours daily is associated with anatomical prolapse [20]. Frequent activities like lifting, bending, and carrying increase biomechanical loads on the pelvic region, further contributes to the risk of prolapse.

Research shows that changes in body position can also impact intra-abdominal pressure and uterine movement [21]. Various body positions exert different stresses on the uterus and its supporting ligaments, thereby influencing physiological alignment. Prolonged heavy lifting often involves repetitive postures, such as standing, excessive forward bending, and backward leaning. Such postures can lead to abnormal tilting of the uterus (forming a 90^∘ angle with the cervix pointing downward) and cervical descent [22]. This reduces the angle between the uterus and vagina, thereby contributing to significant downward prolapse. As the anterior and middle-posterior vaginal walls tilt towards the pubic bone, the posterior wall may adopt a “kneeling” posture, compressing the uterus and rectum against the vaginal wall, potentially leading to uterine and posterior vaginal wall prolapse [18, 22]. However, our study did not identify physical labor as a risk factor for uterine prolapse. Instead, it appeared to have a protective effect, possibly due to the small number of uterine prolapse cases in our sample, particularly the limited number of stage IV cases. Future research should aim to increase sample sizes and conduct stratified analyses to gain a more comprehensive understanding of this issue.

This study has several limitations. Firstly, the recruitment of subjects from our hospital’s postpartum gynecology clinic resulted in a sample predominantly consisting of young women with mild to moderate prolapse, potentially introducing selection bias. Secondly, our study did not analyze the descent or socioeconomic status of the included population, limiting our ability to assess whether the risk of POP is higher among individuals from underdeveloped regions or those facing adverse childbirth conditions. Lastly, the study incorporated a limited number of variables and lacked detailed categorization, which may have restricted the depth of our analysis. Future research should expand the range of variables, conduct long-term follow-ups, and implement prospective cohort studies with larger sample sizes to more comprehensively identify risk factors for POP.

Despite these limitations, our large-scale study is clinically significant in identifying risk factors for POP and implementing early prevention strategies. Our findings indicate that specific groups of women—particularly older mothers, those with two or more vaginal deliveries, those who are obese, and manual laborers—are at higher risk for POP. For these high-risk groups, we propose the following prevention and intervention measures to facilitate early identification and reduce the incidence of POP:

(1) Enhanced screening for high-risk groups: Regular POP screening should be conducted for high-risk groups, including mothers aged $\ge$35 years, those with multiple vaginal deliveries, obese individuals, and manual laborers. These screenings should be integrated into routine gynecological check-ups, especially during the postpartum and perimenopausal periods.

(2) Personalized prevention: Tailored strategies should be developed based on identified risk factors. Postpartum pelvic floor strengthening exercises (e.g., Kegel exercises) should be recommended for older mothers and women with multiple vaginal deliveries. Additionally, education on minimizing abdominal pressure (e.g., adopting proper work posture and using support tools) should be emphasized for manual laborers.

(3) Health education: Raise awareness about POP among high-risk women through healthcare facilities and online platforms. Key educational topics should include the importance of pelvic floor exercises, precautions during manual labor, and postpartum recovery strategies.

(4) Clinical tools development: We plan to develop a POP risk assessment tool based on factors such as age, childbirth history, and occupation, providing personalized risk reports to aid clinical decision-making and follow-up plans for high-risk women.

This study demonstrated that, in patients with POP, grade II prolapse is most prevalent in the anterior vaginal wall, whereas grade I prolapse predominates in the posterior vaginal wall. The incidence of POP is associated with childbearing age, parity, BMI, and mode of delivery, with AMA identified as an independent risk factors. Vaginal delivery specifically increases the risk of vaginal prolapse, while occupations involving prolonged physical labor are associated with an increased risk of posterior vaginal wall prolapse. Addressing these high-risk factors is crucial for the effective prevention of POP. Efforts should focus on disease prevention, enhancing awareness about POP, promoting early detection, and ensuring timely treatment to improve women’s health and quality of life.

All data generated or analyzed during this study are accessible.

DW, QL, YZ and XN: Project development, data collection, manuscript writing. DW, YC, JM and CL: Data collection and analysis. All authors: Manuscript writing and editing. All authors contributed to editorial changes in the manuscript. All authors read and approved the final manuscript. All authors have participated sufficiently in the work and agreed to be accountable for all aspects of the work.

The study was carried out in accordance with the guidelines of the Declaration of Helsinki and approved by the Ethics Committee of West China Second Hospital of Sichuan University (No. 2023179) on September 21, 2023. Informed consent was obtained from all participants. All procedures were performed in accordance with relevant guidelines.

This study was supported by the foundation of Sichuan University (No. 21H0103), Science & Technology Department of Sichuan Province (No. 2019YFS0008), the National Key Research and Development Program of China (No. 2021YFC2009100), the Sichuan Provincial Health Commission Project (No. 21ZD002), Research Projects of Sichuan Science and Technology Department (No. 2023YFQ0070, No. 2023YFS0024), Key Research Projects of Sichuan Science and Technology Department (No. 2023YFG0128, No. 2023NSFSC1606, No. 23ZDYF2049).

The authors declare no conflict of interest.