Nitrous oxide for analgesia in external cephalic version at term: prospective comparative study.

Objective: The objective of this study was to analyze the effect of using inhaled nitrous oxide (N2O) for analgesia in external cephalic version (ECV) at term on the success rate of the procedure, on pain, and on obstetric and perinatal outcomes.

Methods: A prospective comparative cohort study among 300 women with singleton pregnancy in breech presentation at term undergoing an ECV with inhaled N2O in a 50:50 mix with oxygen for analgesia and 150 ECVs with no analgesia.

Results: The success rate was 52.