Obese women have an increased risk of preterm birth. Cerclage is used for prevention in a subset of these women with cervical insufficiency. We aimed to quantify the difference in risk of preterm birth in pregnancies treated with cerclage for cervical insufficiency in an obese population compared to a non-obese population.METHODS:
This is a retrospective cohort study. All cerclage procedures from January 1, 2011 to December 31, 2016 were collected from a single center. Groups were defined as obese (BMI 30.0 or greater) and controls(BMI <30.0). The primary endpoint was defined as preterm birth <23 weeks. Secondary outcomes included preterm birth <28, 32, or 37 weeks. Groups were also compared regarding cerclage type (McDonald vs Shirodkar). Odds ratios with 95% confidence intervals were calculated for each outcome.RESULTS:
267 cerclage procedures were collected. Delivery documentation was complete for 225 (109 obese, 116 non-obese controls). Gestational age at delivery did not differ significantly (33 weeks in obese vs 34.33 weeks in non-obese, p = 0.14). Risk of preterm delivery for obese women undergoing cerclage was not significantly different from controls. When cerclage type was compared, obese women undergoing Shirodkar cerclage were at increased risk of preterm delivery compared to controls(OR 4.29, 95% CI 1.14-16.2), this difference was not noted in those undergoing McDonald cerclage.CONCLUSION:
Obesity does not increase the rate of preterm delivery with cerclage, but Shirodkar-type cerclage independently increases the risk of prematurity in this population.