Involuntary Leaks: Study Investigating Stress Urinary Incontinence During Pregnancy

Pelvic floor dysfunction (PFD) presents significant issues related to pelvic organ abnormalities and dysfunction, particularly in the context of pregnancy and vaginal childbirth, which are recognized risk factors. Recent study aimed to enhance understanding of how pregnancy influences pelvic floor parameters and their association with stress urinary incontinence (SUI). Notably, SUI, characterized by involuntary urine loss when intra-abdominal pressure increases, is prevalent during pregnancy, with reported incidence rates varying widely among studies.

Methodology of Research

Utilizing three-dimensional transperineal ultrasound, the research investigated pelvic floor biometry across three trimesters (first: 10-13 weeks, second: 26-28 weeks, third: 35-38 weeks) in 385 pregnant women. Significant changes in pelvic floor anatomical parameters, including hiatal area (HA), anteroposterior (AP) diameter, and transverse diameter, were observed as pregnancy progressed. Statistical analysis indicated gradual increases in these measurements among trimesters (P<0.001), while pubic arch angle remained stable (P=0.596).

Results on Positioning and SUI Incidence

Bladder neck and rectal ampulla positions also showed significant variances with respect to the trimester, particularly at maximal Valsalva maneuver (VM), indicating that pelvic organ positioning is affected by gestational changes. SUI incidence increased notably in the third trimester, validated through comparative analysis with non-SUI groups, where a significant difference in transverse diameter during pelvic floor muscle contraction (PFMC) was noted (P=0.048).

Predictors of Stress Urinary Incontinence

Logistic regression identified independent predictors for SUI including age, BMI, and HA, illustrating that higher BMI and altered pelvic dimensions significantly correlate with SUI risk (P<0.001, AUC=0.778). Furthermore, while no significant differences in pelvic parameters were detected between SUI and non-SUI in early pregnancy, the incidence of abnormal posterior bladder and urethral rotation angles escalated in the second and third trimesters, underscoring pregnancy’s critical role in pelvic floor alterations.

Discussion and Conclusions

Important discussions emerged regarding the impact of muscle compliance and functional aspects of pelvic floor support, suggesting that even women with similar anatomical configurations may differ in SUI presentation due to individual muscle characteristics. The findings emphasize the need to consider pregnancy as a pivotal period for evaluating pelvic health, advocating for proactive interventions to mitigate SUI risk postpartum. Limitations include selection bias and the inability to control for unmeasured confounders, alongside the study's cross-sectional design which does not factor in longitudinal changes within individuals. In conclusion, the research provides a predictive model for SUI informed by anatomical changes during pregnancy, aiming to guide targeted treatments for expectant mothers.

Key Points

- -Impact of Pregnancy on Pelvic Floor Anatomy-: Significant changes in pelvic floor anatomical parameters, such as hiatal area, anteroposterior diameter, and transverse diameter were observed across trimesters, particularly between the first (10-13 weeks) and third (35-38 weeks), indicating a measurable evolution in pelvic floor configuration during gestation (P<0.001).

- -Bladder and Rectal Position Dynamics-: During the maximal Valsalva maneuver, notable differences in the positions of the bladder neck and rectal ampulla were recorded across trimesters, illustrating the influence of gestational changes on pelvic organ positioning.

- -Increased Incidence of Stress Urinary Incontinence (SUI)-: A pronounced increase in SUI incidence was documented in the third trimester compared to non-SUI groups, correlated with significant changes in the transverse diameter during pelvic floor muscle contraction (P=0.048).

- -Predictors of SUI-: Logistic regression analysis identified age, BMI, and hiatal area as independent predictors of SUI, with elevated BMI and certain pelvic dimension changes indicating heightened risk (P<0.001, AUC=0.778), while abnormal posterior bladder and urethral rotation angles became more prevalent in the later trimesters.

- -Functional Variability Despite Similar Anatomy-: Individual differences in muscle compliance and pelvic floor support dynamics were highlighted, suggesting that anatomical similarity does not uniformly predict SUI occurrence, emphasizing the complexity of individual pelvic floor health.

- -Recommendations and Limitations-: The findings advocate for proactive pelvic health assessments during pregnancy, alongside targeted treatments postpartum to address SUI risk. Limitations noted include potential selection bias, unmeasured confounders, and the cross-sectional nature of the study that restricts longitudinal analysis within the same individuals.

Reference –

Chuanqing Sun et al. (2025). Pelvic Floor Structural Changes During The First Singleton Pregnancy And The Risk Factors Of Stress Urinary Incontinence. *BMC Pregnancy And Childbirth*, 25. https://doi.org/10.1186/s12884-025-07666-1.