The impact of cerclage in twin pregnancies on preterm birth rate before 32 weeks

Abstract

Purpose: To evaluate whether cerclage in twins reduces the rate of spontaneous preterm birth <32 weeks when compared to expectant management.

Methods: This is a retrospective cohort study of twin pregnancies with the following indications for cerclage from two institutions: history of prior preterm birth, ultrasound-identified short cervix ≤2.5 cm, and cervical dilation ≥1.0 cm. The “cerclage” cohort received a cerclage from a single provider at a single institution from 2003–2016. The “no cerclage” group included all patients with similar indications that were expectantly managed from 2010–2015, at a second institution where cerclages are routinely not performed in twin pregnancies. The primary outcome was the rate of spontaneous preterm birth at <32 weeks. Secondary outcomes were the rates of spontaneous and overall (including medically indicated) preterm births at <32 weeks, < 34 weeks, and <36 weeks, chorioamnionitis, birth weight, and neonatal mortality within 30 days of life. We also performed a planned subgroup analysis stratified by cerclage indication.

Results: In all, 135 women were included in two cohorts: cerclage (n = 96) or no cerclage (n = 39). The rates of spontaneous preterm birth <32 weeks were 10.4% (n = 10) with cerclage versus 28.2% (n = 11) without cerclage (OR 0.23, CI 0.08–0.70, p = .017). After adjusting for cerclage indication, clinical history, age, chorionicity, insurance type, race, BMI, in-vitro fertilization, and multifetal reduction, there remained a significant reduction in the cerclage group of spontaneous preterm birth <32 weeks (adjusted odds ratio (aOR) 0.24, CI 0.06–0.90, p = .035), spontaneous preterm birth <36 weeks (aOR 0.34, CI 0.04–0.81, p = .013) as well as in overall preterm birth <32 weeks (aOR 0.31, CI 0.1–0.86, p = .018), and overall preterm birth <36 weeks (aOR 0.37, CI 0.10–0.84, p = .030). When stratified by short cervix or cervical dilation in the cerclage versus no cerclage groups, there was a significant decrease in spontaneous preterm birth <32 weeks in the cerclage group with cervical dilation (11.1 versus 41.2%, p = .01) but not in the cerclage group with short cervix only, even for cervical length <1.5 cm. Pregnancy latency was 91 days in the cerclage group versus 57 days in the no cerclage group (p = .001), with a median gestational age at delivery of 35 versus 32 weeks (p = .002). There was no increase in chorioamnionitis in the cerclage group. Furthermore, there was a significant increase in birth weight (median 2278 versus 1665 g, p < .001) and decrease in perinatal death <30 days (1.6 versus 12.9%, p = .001).

Conclusions: Cerclage in twin pregnancies significantly decreased the rate of spontaneous preterm birth <32 weeks compared to expectant management. However, when stratified by cerclage indication, this decrease in primary outcome only remained significant in the group with cervical dilation.

Keywords:

• Prematurity
• multiple gestation
• rescue
• short cervix
• cervical insufficiency

Disclosure statement

The authors report no conflicts of interest. The views expressed in the submitted article are of the authors and not an official position of the institution.

Additional information

Funding

S.LG. is supported by the Reproductive Scientist Development Program, by the Eunice Kennedy Shriver National Institute of Child Health & Human Development [K12HD000849] and the Burroughs Wellcome Fund.