Differences in urinary incontinence symptoms and pelvic floor structure changes during pregnancy between nulliparous and multiparous women

Background This study was performed to compare changes in urinary incontinence (UI) symptoms and pelvic floor structure during pregnancy between nulliparous and multiparous women. Methods A cross-sectional survey was performed among pregnant women from July 2016 to January 2017. In total, 358 pregnant women from two hospitals underwent an interview and pelvic floor transperineal ultrasound assessment. A questionnaire regarding sociodemographic, gynecological, obstetric features and the International Consultation on Incontinence Questionnaire-Short Form (ICIQ-SF) were used for the interview. Imaging data sets were analyzed offline to assess the bladder neck vertical position (BNVP), urethral angles (α, β, and γ angles), and hiatal area (HA) at rest and at maximal Valsalva maneuver (VM). Results After excluding 16 women with invalid data, 342 women were included. The prevalence ( χ 2  = 9.15, P = 0.002), frequency ( t = 2.52, P = 0.014), usual amount of UI ( t = 2.23, P = 0.029) and scores of interference with daily life ( t = 2.03, P = 0.045) during pregnancy were higher in multiparous than nulliparous women. A larger bladder neck descent (BND) ( F = 4.398, P < 0.001), HA ( F = 6.977, P < 0.001), α angle ( F = 2.178, P = 0.030), β angle ( F = 4.404, P < 0.001), and γ angle ( F = 2.54, P = 0.011) at VM were discovered in pregnant women with UI than without UI. Multiparous women had a significantly higher BND ( t = 2.269, P = 0.024) and a larger α angle ( F = 2.894, P = 0.004), β angle ( F = 2.473, P = 0.014), and γ angle ( F = 3.255, P = 0.001) at VM than did nulliparous women. Conclusion Multiparous women experienced more obvious UI symptoms and pelvic floor structure changes during pregnancy than did nulliparous women.