Physical Exam Indicated Cerclage in Twin Gestations

Twin pregnancies have 58% incidence of preterm delivery (before 37 weeks of gestation), with increased perinatal mortality and neonatal morbidity. No therapy has proven effective in preventing preterm birth in twins. When cervical dilation is identified before 24 weeks in singleton pregnancies, the risk of preterm birth is 90%-100%; based on a small series of cases, approximately 50% of twin gestations with cervical dilation will be delivered prior to viability (24 weeks) and the risk of preterm birth prior to 34 and 37 weeks was 85% and 100%. Cervical dilation is the worst prognostic factor for preterm birth. There are a small number of case reports of cervical cerclage in twin pregnancies with a dilated cervix that suggest similar outcomes to those in singleton pregnancies. The investigators' objective is to determine if physical exam indicated cerclage reduces the incidence of spontaneous preterm birth \<34 weeks and improve perinatal outcome in asymptomatic women with twin gestations and dilated cervix (1 to 5 cm) between 16 to 23 6/7 weeks of gestation.