Progesterone supplementation after cerclage does not improve the preterm birth rate

Objective The goal of this study is to evaluate whether adjuvant progesterone following cerclage affords reduction in the rate of preterm delivery. Study design This is a retrospective cohort review of all individuals who underwent transvaginal cerclage placement at a tertiary care academic medical center between 2005 and 2021. The rate of delivery prior to 37 weeks and several secondary maternal and neonatal outcomes were compared between patients with and without progesterone supplementation after cerclage. Multivariable regression, subgroup, and matched pairs analyses were performed in order to account for the formulation of progesterone, indication for cerclage, and other potential confounding variables. The study was powered a priori to detect a difference in our primary outcome. Results Among 451 patients, there were 163 history-, 135 ultrasound-, and 153 examination-indicated cerclages. Overall, 284 (63%) received adjuvant progesterone. Adjuvant progesterone was associated with an increased rate of preterm delivery before 37 weeks (45% v. 34%, p=0.03) with an adjusted odds ratio of 1.78 (95% confidence interval 1.14, 2.80) in our multivariable model. The median latency from cerclage placement to delivery was shorter when progesterone was used (119 v. 139 days, p<0.001). There was no benefit of adjuvant progesterone when analyzed by formulation of progesterone or indication for cerclage or when analyzing pairs matched based on propensity score matching. There were no differences in secondary outcomes for pregnant patients or their offspring. Conclusion Adjuvant progesterone does not decrease the preterm delivery rate and may in fact cause harm by decreasing latency from cerclage to delivery. Maternal and neonatal outcomes do not vary with supplemental progesterone after cerclage. Our data do not support a synergistic benefit of cerclage and post-cerclage progesterone.