Factors associated with a successful external cephalic version in the early ECV trial.

OBJECTIVES The objective of this research was to determine factors that were associated with a successful external cephalic version (ECV) procedure. METHODS We undertook a secondary analysis of data from a randomized controlled trial, The Early External Cephalic Version (Pilot) Trial. In this secondary analysis, we included data for the subset of 178 women who had an ECV as part of the pilot trial (123 nulliparous women with any breech presentation and 55 multiparous women with a frank breech presentation only). Using this dataset, we began with two separate univariate analyses, one of characteristics that could be determined before undertaking a procedure, and the other of factors associated with the ECV procedure itself. Variables that had a P value of < or = 0.1 in the univariate analyses were included in two separate logistic regression models, one for preprocedural and one for procedural factors, using a backward elimination approach. RESULTS Multiparity and a non-engaged presenting part were significant preprocedural predictors of ECV success. Procedural factors predictive of ECV success included lower reported maternal pain scores during the procedure, a single attempt at ECV, and a more mobile fetus. CONCLUSION Non-engagement of the presenting part was the only modifiable factor predicting ECV success that was identified in this analysis, and it supports the hypothesis that beginning the ECV procedure earlier in pregnancy, prior to engagement, may have merit. The Early ECV 2 Trial is in progress and will further test this hypothesis.