Cervical length at 30-32 weeks and the risk of Cesarean delivery in twin pregnancies

Objectives To estimate the association between the cervical length (CL) measurement at 30-32 weeks and the mode of delivery in twin pregnancies. Methods This was a retrospective study of a cohort, from 2005-2010, of 265 twin pregnancies with a CL measurement at 30-32 weeks. We compared the CL measurement at 30-32 weeks based on mode of delivery. We then analyzed our data across four subgroups, based on the CL measurement quartiles at 30-32 weeks. We performed this analysis in all patients, and also performed a planned subgroup analysis of 130 patients who attempted a vaginal delivery. Results In all patients, including those who attempted a vaginal delivery, the mean CL at 30-32 weeks was significantly shorter in women who delivered vaginally compared with women who had a Cesarean section. The likelihood of Cesarean delivery increased significantly with increasing CL measurement across the groups defined by measurement quartiles. On adjusted analysis controlling for maternal age, race, in-vitro fertilization, chorionicity, induction of labor and prior vaginal delivery, the CL measurement at 30-32 weeks was independently associated with mode of delivery. Conclusions In twin pregnancies, the CL at 30-32 weeks is significantly associated with the likelihood of Cesarean delivery. A longer CL may represent underdevelopment of the uterus, leading to a higher risk of Cesarean delivery in labor at term.