Both groups (primiparae and multiparae) were comparable in terms of age, BMI, gestational age and birthweight. The majority of participants (86.2%, n = 56) was Caucasian. 80.0% (n = 52) had given birth by non-instrumental vaginal delivery, 20.0% (n = 13) by vacuum extraction, none by forceps.
A significant difference between the MV1 to 4 of primiparous and multiparous women was demonstrated, with T-values and p-values of respectively t(44)=3.88 (p <.001) for MV1, t(44)=3.82 (p <.001) for MV2, t(44)=2.65 (p =.012) for MV3 and t(44)=2.54 (p =.015) for MV4. MV 1 and 2 had the greatest effect sizes with Cohen’s d=0.54 (95% CI [-1.77, -.52]) and d=0.48 (95% CI [-1.73, -.48]) respectively, followed by MV3 (d=0.39, 95% CI [-1.36, -.16]) and MV4 (d=0.28, 95% CI [-1.33, -.14]). The assumption of normality was not fulfilled for MV5 and MV6. A significant difference between primiparae and multiparae was found for MV6 (U=150.00, exact sig. two-tailed =.012), but not for MV5 (U=199.50, exact sig. two-tailed =.237). MV1 and MV2 were almost perfectly correlated to each other and strongly correlated with MV3 and MV4. Of all tested confounders, only the overall highest grade of perineal rupture was found to have a significant negative effect on proximal urethral mobility. Univariate generalized linear regression analysis was performed for each of the mobility vectors to investigate the predictive value of parity and the statistically significant correlated factors. Multiparity predicted urethral mobility for MV1 (R2=.26, F(1,44)=15.1, p<.001), MV2 (R2=.24, F(1,44)=14.1, p<.001), MV3 (R2=.13, F(1,44)=6.76, p=.013), MV4 (R2=.13, F(1,44)=6.27, p=.016) and MV6 (R2=.12, F(1,44)=6.20, p=.017). When overall highest grade of perineal rupture is added to the regression model, the difference in MV1 is predicted for adjusted R2=.28, F(2,43)=9.79, p<.001 and in MV2 for adjusted R2=.29, F(2,43)=10.15, p<.001.