. Author manuscript; available in PMC: 2014 Nov 16.

Published in final edited form as: Cochrane Database Syst Rev. 2010 Sep 8;(9):CD007396. doi: 10.1002/14651858.CD007396.pub2

Analysis 23.1. Comparison 23 IV fentanyl versus IV butorphanol, Outcome 1 Additional analgesia required (women requesting two or more doses).

Review: Parenteral opioids for maternal pain management in labour

Comparison: 23 IV fentanyl versus IV butorphanol

Outcome: 1 Additional analgesia required (women requesting two or more doses)