Voiding function in pregnancy and puerperium.

Bladder function changes significantly in pregnancy. This study prospectively examined voiding function in a nulliparous cohort. A total of 200 nulliparous women were seen twice during pregnancy and 2-5 months postpartum. Flowmetry, ultrasound estimation of residual urine and translabial ultrasound of bladder neck mobility were evaluated. The Liverpool nomograms were used to calculate maximum and average flow rate (MFR and AFR) centiles. Flowmetry was available on 186 women at 6-18 weeks, 165 women at 32-39 weeks and 162 women 2-5 months postpartum. Voided volumes decreased from 253 to 180 ml during pregnancy (p<0.001), increasing again to 198 ml postpartum. MFR centiles increased during pregnancy [from 49 (SD 28) to 58 (SD 29), p=0.003], and this trend continued postpartum [to 61.8 (SD 26.8), p<0.001]. Changes correlated weakly but significantly with changes in several parameters of bladder neck mobility (e.g. urethral rotation and MFR centiles, r=0.182, p=0.027). MFR and AFR centiles increase in pregnancy and with childbirth, and increases correlate weakly with changes in bladder neck mobility.