Cerclage doesn't prevent preterm birth
While it is true that having a shorter cervix is associated with preterm delivery, cervical cerclage with a Shirodkar suture makes no difference in the outcome, according to a randomized, controlled trial of more than 47,000 pregnant women in various countries.
Researchers randomized women with a cervix of 15 mm or less in length to receive either cervical cerclage or expectant management. The proportion of preterm deliveries before 33 weeks' gestation was similar in both groups: 22% in the cerclage group vs. 26% of controls. The procedure also did not reduce perinatal morbidity or mortality.
To MS, Alfirevic Z, Heath VCF, et al. Cervical cerclage for prevention of preterm delivery in women with short cervix: randomised controlled trial. Lancet. 2004;363:1849-1853.
