Does pregnancy affect pelvic organ mobility?

It is generally accepted that parity is a strong predictor of pelvic organ prolapse and incontinence. However, controversy persists as to whether this effect is due to pregnancy itself or parturition.

To define the contribution of early and late pregnancy to bladder mobility.

Case control series, using 88 non-pregnant control subjects recruited for a heritability study on urinary incontinence and prolapse, matched for age and ethnicity with 28 pregnant women seen at 10-17 weeks and again at 32-39 weeks' gestation. Main outcome parameters were ultrasound measures of anterior, central and posterior compartment descent as well as joint mobility measurements.

Patients in early pregnancy showed higher values for bladder mobility in comparison with non-pregnant controls, although this did not reach significance for all parameters. However, when late pregnancy data were tested against non-pregnant controls, this difference reached significance for all tested parameters. Uterine and rectal descent did not show any significant differences between groups. Results for joint mobility were inconsistent.

This study supports the hypothesis that bladder and urethral mobility increase in pregnancy. This effect is already noticeable at 6-18 weeks. As similar changes are also seen in elbow hyperextension, a generalised effect on connective tissue biomechanics, likely hormonal, can be hypothesised.