Effectiveness of cerclage according to severity of cervical length shortening: A meta-analysis

textabstractObjectives To estimate the effectiveness of cerclage according to degree of cervical length (CL) shortening. Methods A meta-analysis was carried out of trials of women with singleton gestations and second-trimester transvaginal sonographic CL <25 mm randomized to cerclage or no cerclage. The degree of CL shortening was correlated to the efficacy of cerclage in preventing preterm birth. Results There was a significant reduction in preterm birth <35 weeks in the cerclage compared with no cerclage groups in 208 singleton gestations with both a previous preterm birth and CL <25 mm (relative risk, 0.61; 95% CI, 0.40-0.92). In these women, preterm birth <37 weeks was significantly reduced with cerclage for CL ≤5.9 mm, ≤15.9 mm, 16-24.9 mm and <25 mm. None of the analyses for 344 women without a previous reterm birth was significant. Conclusions Cerclage, when performed in women with a singleton gestation, previous preterm birth and cervical length