H . Yazdi Moghaddam [1] , F . Rahnamai Rahsepar [2] , A . Heydari [3] Received: 11/07/2009 Sent for Revision: 23/01/2010 Received Revised Manuscript: 20/11/2010 Accepted: 26/12/2010 Background and Objectives : Delivery is one of the greatest events in the life of a pregnant woman. Although it is considered to be a natural phenomenon, it is potentially dangerous. Entonox gas us...
