Background: Pelvic floor muscle exercises (PFME) are commonly recommended during pregnancy and after birth for both prevention and treatment of lower urinary tract symptoms (LUTS). Stress urinary incontinence has long been presumed to be associated with urethral hypermobility. Pregnancy and delivery are known cause of increasing bladder neck descent (BND).
Objective: The present study aimed to determine the effect of antenatal PFME on bladder neck descent in nulliparous
pregnancy.
Material and Method: 219 nulliparous women pregnant between 8-12 weeks were interviewed and then underwent transperineal ultrasound. Of the total, 108 women were randomly assigned to a PFMT group, while 111 women to a control group. The latter group received routine antenatal care. For the intervention group, patients were taught about PFMT using visual biofeedback by transperineal ultrasound. The PFMT regimen comprised a series of 15 contractions, and each contraction was held for 5 seconds, with 5 seconds rest between each contraction. Patients were asked to repeat this regimen for 3 times after each meal. At second trimester, third trimester, 3-month postpartum and 6-month postpartum, the subjects in both groups were interviewed and then underwent another ultrasound assessment. Transperineal ultrasound was performed after bladder emptying, with the patient in the supine position. Bladder neck position was measured at rest and on maximal valsava, and the differences yielded a numerical value for BND. The sample size was calculated with a power of 80% p<0.05 was considered significant. SPSS 15.0 for windows (SPSS Inc., Chicago, Illinois) was used for statistical analyses.
Results: Demographic characteristics did not differ significantly between PFMT and control groups, showing effective randomization. Mean age was 26.95+3.94 and 26.51+5.41 years for PFMT and control group, respectively (p = 0.49). There were no significant differences in bladder symptoms between the two groups at the first visit. In the first trimester, the average BND of the PFMT group was slightly higher than BND of the control group (14.1+6.9 mm and 12.2+6.7 mm respectively (p = 0.04)). When comparing delivery mode by using Pearson’s Chi-square test, there was no statistically significant difference between two groups (p = 0.35). The mean fetal birth weight of women in the PFMT group was 3,084
grams and in the control group was 3,093 grams (p = 0.88). At 6 months postpartum, 80 women of the PFMT group and 65 women of the control group returned for follow-up. There were no differences regarding the prevalence of LUTS between the groups at 6 months after delivery. Women in the control group had a higher BND (16.4+6.6 mm) than those in the PFMT group (13.9+7.3 mm, p = 0.03). This difference was also found in the subgroup of the women who delivered vaginally (BND = 17.5+6.7 mm in the control group and 13.2+7.4 mm in the PFMT group, p = 0.006).
Conclusion: Although postpartum prevalence of LUTS was no different between groups, this study has demonstrated that antenatal pelvic floor muscle exercises may reduce bladder neck mobility at 6 months after childbirth. The significance of such an effect remains to be determined.

Keywords: Transperineal ultrasound, Bladder neck descent, Pregnancy, Delivery