The effect of cervical cerclage on the labor curve

Cervical cerclage is an effective intervention to prevent preterm birth among individuals with a history of cervical insufficiency, individuals with a short cervix and history of preterm birth, or individuals with second-trimester painless dilation. Although cerclage reduces the mechanical stress on the cervix by reinforcing it with sutures, cerclage could also cause scarring of the cervix, which may affect the progress of labor.

This study aimed to compare the labor curves between individuals who underwent cerclage and those who did not undergo cerclage.

This was a retrospective cohort study of individuals with singleton term pregnancy, vertex presentation, and vaginal delivery, using the data from the Consortium on Safe Labor. We excluded individuals with fetal anomalies, stillbirth, or abnormal perinatal outcomes, including 5-minute Apgar score of <7, birth injury, and neonatal intensive care unit admission. We modeled the course of cervical dilation using repeated-measures analysis with a polynomial function and generated smoothed labor curves. An interval-censored regression analysis was performed to estimate traverse times (the elapsed time between 2 cervical dilation measures). The traverse times were compared between individuals who underwent cerclage and those who did not undergo cerclage, controlling for induction of labor and parity.

There were 245 individuals who underwent cerclage and 110,080 individuals who did not undergo cerclage. Individuals who underwent cerclage compared with those who did not undergo cerclage had a similar traverse time from 1 to 6 cm (median, 9.1 vs 10.3 hours; adjusted P=.37) and from 6 to 10 cm (median, 1.5 vs 1.5 hours; adjusted P=.23). Individuals who underwent cerclage compared with those who did not undergo cerclage had a longer traverse time from rupture of membranes to delivery (median, 4.0 vs 3.0 hours; adjusted P<.01).

Cervical cerclage did not affect the overall progress of labor.