Change in levator ani muscle stiffness and active force during pregnancy and post-partum

Potential role of physical labor and cultural views of menstruation in high incidence of pelvic organ prolapse in Nepalese women: a comparative study across the menstrual cycle

Introduction

Pelvic organ prolapse (POP) is a significant health concern for young Nepali women, with potential risk factors including pelvic floor trauma from vaginal delivery and heavy lifting. The prevalence of symptomatic POP (SPOP) among nulliparous women in Nepal is 6%, while the general population of Nepali women aged 15-49 years reports a prevalence of 7%. Surprisingly, the average age of SPOP onset in Nepal is 27 years, challenging the assumption that postmenopausal age and vaginal delivery are the sole risk factors. This study aims to investigate the influence of increased intra-abdominal pressure (IAP) during lifting tasks on pelvic organ descent in Nepali women across different menstrual cycle stages.

Methods

The study included 22 asymptomatic Nepali women aged 18-30 years who regularly engage in heavy lifting. Intra-abdominal pressure was measured intra-vaginally during typical and simulated lifting tasks, which encompassed various scenarios such as ballistic lifting, ramped lifting, and pre-contraction of pelvic floor muscles, as well as coughing, Valsalva maneuver, and pelvic floor contractions. Pelvic floor displacement was recorded using transperineal ultrasound during menstruation, ovulation, and the mid-luteal phase.

Results

Results indicated that pelvic floor displacement was greater during menstruation than ovulation when performing a simulated ballistic lifting task (6.0 ± 1.6 mm vs. 5.1 ± 1.5 mm, p = 0.03, d = 0.6). However, there was no significant difference in pelvic floor displacement during lifting when the pelvic muscles were pre-contracted.

Conclusion

These findings suggest that lifting heavy loads during menstruation may increase the risk of stretching and injuring pelvic floor supportive tissues, potentially contributing to SPOP in young Nepali women. Pre-contracting pelvic floor muscles during lifting tasks may offer a protective effect. Understanding these factors could aid in developing targeted preventive measures and raising awareness about the impact of heavy lifting on pelvic floor health among Nepali women.

Morphological Variation in the Pelvic Floor Muscle Complex of Nulliparous, Pregnant, and Parous Women

Specific levator ani muscle imaging measures change with pregnancy and vaginal parity, though entire pelvic floor muscle complex (PFMC) shape variation related to pregnancy-induced and postpartum remodeling has never been quantified. We used statistical shape modeling to compute the 3D variation in PFMC morphology of reproductive-aged nulliparous, late pregnant, and parous women. Pelvic magnetic resonance images were collected retrospectively and PFMCs were segmented. Modes of variation and principal component scores, generated via statistical shape modeling, defined significant morphological variation. Nulliparous (have never given birth), late pregnant (3rd trimester), and parous (have given birth and not currently pregnant) PFMCs were compared via MANCOVA. The overall PFMC shape, mode 2, and mode 3 significantly differed across patient groups (p < 0.001, = 0.002, = 0.001, respectively). This statistical shape analysis described greater perineal and external anal sphincter descent, increased iliococcygeus concavity, and a proportionally wider mid-posterior levator hiatus in late pregnant compared to nulliparous and parous women. The late pregnant group was the most divergent, highlighting differences that likely reduce the mechanical burden of vaginal childbirth. This robust quantification of PFMC shape provides insight to pregnancy and postpartum remodeling and allows for generation of representative non-patient-specific PFMCs that can be used in biomechanical simulations.

Effect of prolonged second stage of labor on pelvic floor function: A prospective cohort study

INTRODUCTION AND HYPOTHESIS

To evaluate the effect of the second stage of labor (SSL) lasting > 2 h on pelvic floor function.

METHODS

This single-center prospective cohort study included primiparous women with SSL > 2 h treated at Tongji Hospital between January 2018 and December 2019 (case group). A matched group of women with similar newborn weight and SSL < 2 h were recruited simultaneously (control group). Stress urinary incontinence (SUI) and pelvic floor muscle (PFM) characteristics were measured at 6 weeks, 6 months, and finally 1 year postpartum.

RESULTS

A total of 63 pairs of primiparous women completed 1-year follow-up. The incidence of SUI in the case group was significantly higher than that in the control group at 6 weeks postpartum (P = 0.020); however, the differences were not significant at 1 year postpartum (P=1.00). PFM endurance was significantly lower in the case group at 6 weeks (P = 0.000), 6 months (P = 0.000), and 1 year (P = 0.011) after childbirth. There was no difference in PFM strength between the two groups. The maximal voluntary contraction (MVC) of PFM was significantly lower in the case group at 6 weeks postpartum (P = 0.007), but the differences were not significant at 1 year postpartum (P = 0.197). PFM endurance and MVC were higher at 1 year than at 6 weeks postpartum in both groups.

CONCLUSIONS

The SSL > 2 h increased the incidence of SUI at 6 weeks postpartum and decreased PFM endurance for 1 year.