Risk of Recurrent Preterm Prelabour Rupture of Membranes: Role of Mid-Trimester Cervical Length Assessment

Individuals with prior preterm prelabour rupture of membranes (PPROM) are at increased risk of recurrence, yet tools to stratify risk in subsequent pregnancies remain limited. Given that PPROM contributes to nearly one-third of all spontaneous preterm births, improved predictive strategies are critical for individualized counselling. This study aimed to identify maternal, clinical, and ultrasound-based factors associated with PPROM recurrence.

We conducted a retrospective cohort study of 343 individuals with a singleton pregnancy following prior PPROM (14⁰-36⁶ weeks), managed at a tertiary preterm birth clinic between 2011 and 2024. In the subsequent pregnancy, all underwent serial transvaginal cervical length measurements from 16 to 24 weeks, with frequency guided by cervical findings. The primary outcome was recurrent PPROM. Multivariable logistic regression with multiple imputation identified independent predictors.

Most patients (78%) received vaginal progesterone in the subsequent pregnancy. Recurrent PPROM occurred in 16% of pregnancies. Among these, 83% delivered preterm, with 41% delivering before 34 weeks. A short cervix (<25 mm) at 24 weeks was associated with an increased risk of recurrence (aOR 2.33, 95% CI 1.07-5.08).

In individuals with prior PPROM, a short cervix at 24 weeks is associated with increased risk of recurrence despite vaginal progesterone use. These findings support the use of standardized mid-trimester cervical assessment to inform individualized risk stratification and counselling.