Interpregnancy Interval and the Degree of Cystocele Across Two Vaginal Deliveries: A Retrospective Self-Controlled...

To examine the association between interpregnancy interval (IPI) and the risk of worsening cystocele between two consecutive vaginal deliveries.

In this retrospective cohort study, 314 women who underwent transperineal ultrasound (TPUS) within six months postpartum after each of two consecutive vaginal deliveries were included. Multivariable linear regression was used to assess the association between first-delivery cystocele severity and second-delivery outcomes, with IPI categorized as ≤24, >24-≤36, and >36 months to evaluate its potential modifying effect.

Cystocele severity after the first delivery strongly predicted worsening at the second delivery (β = 0.5; 95% CI: 0.4-0.6; p < 0.001). Longer IPI was associated with less progression of cystocele, showing a significant linear trend across IPI categories (p for trend = 0.04). After adjusting for obstetric factors, the position of the most dependent point of the posterior bladder wall after the first delivery was independently associated with cystocele severity after the second delivery (β = 0.5; 95% CI: 0.4-0.6; p < 0.001). IPI was negatively associated with cystocele severity. Although the formal test for interaction was not statistically significant (p for interaction = 0.11), the test for linear trend across IPI strata was significant (p for trend = 0.04).

Cystocele severity after the first vaginal delivery strongly predicts that after the second, and this association weakens with longer IPI. TPUS enables early identification of high-risk women, supporting individualized birth spacing counseling with potential public health implications for the prevention of pelvic floor disorders.