Association of cervical pessary use with preterm birth in singleton pregnancies with a short cervix and threatened preterm labor: a retrospective cohort study

Background Preterm birth remains a leading cause of neonatal morbidity and mortality worldwide. A short cervix is a strong predictor of spontaneous preterm birth, and cervical pessary placement has been proposed as a noninvasive intervention to reduce this risk. However, randomized trials evaluating cervical pessary use have produced inconsistent results, and evidence regarding pessary use specifically in women with both threatened preterm labor and a short cervix remains limited. This study evaluated the association between cervical pessary use and perinatal outcomes in this population. Methods This single-center retrospective cohort study included women with singleton pregnancies diagnosed with threatened preterm labor and a short cervix (≤ 25 mm) between 18 + 0 and 29 + 6 weeks of gestation. Women treated with a cervical pessary between April 2021 and March 2024 were compared with historical controls managed between April 2017 and March 2020. Women receiving vaginal progesterone therapy or cervical cerclage were excluded. The primary outcome was preterm birth before 37 weeks of gestation. The secondary outcomes were preterm birth before 36, 34, and 28 weeks; maternal management parameters; and neonatal outcomes. Multivariable logistic regression and propensity score-adjusted analyses were performed. Results Among 180 eligible women (90 in each group), preterm birth before 37 weeks occurred in 20.9% of the pessary group and 51.2% of the control group. Cervical pessary use was independently associated with delivery at or beyond 37 weeks (adjusted odds ratio [aOR], 4.65; 95% confidence interval [CI], 2.21–9.78; P < 0.001). Significant associations were also observed for delivery at or beyond 36 weeks (aOR, 2.64; 95% CI, 1.12–6.22) and 34 weeks (aOR, 2.94; 95% CI, 1.07–8.11), whereas no statistically significant association was observed for delivery at or beyond 28 weeks. The pessary group had shorter hospitalization and reduced exposure to intravenous tocolytic therapy, without evidence of increased neonatal morbidity. Conclusions Cervical pessary use in women with threatened preterm labor and a short cervix was associated with prolongation of gestation and reduced maternal treatment intensity, without evidence of increased severe neonatal morbidity. These findings should be interpreted cautiously given the retrospective design and use of historical controls.