6Ohel G,Gonen R,Vaida S,et al.Early versus late initiation of epidural analgesia in labor.,does it increase the risk of cesarean section? A randomized trial.Am J Obstet Gynecol,2006,194:600-605.
7Wong CA,Scavone BM,Peaceman AM,et al.The risk of cesarean delivery with neuraxial analgesia given early versus late in labor.N Engl J Med,2005,352:655-665.
8Torvaldsen S,Roberts CL,Bell JC,et al.Discontinuation of epidural analgesia late in labour for reducing the adverse delivery outcomes associated with epidural analgesia.Cochrane Database Syst Rev,2004,(4):CD004457.
9Boselli E,Debon R,Cimino Y,et al.Background infusion is not beneficial during labor patient-controlled analgesia with 0.1% ropivacaine plus 0.5 mg/ml sufentanil.Anesthesiology,2004,100:968-972.
10Stienstra R, Jonker T, Bourdrez P et al. Ropivacaine 0. 25% versus bupivacaine 0.25% for continuous epidural analgesia in labor : a double blind comparison [J]. Anesth Analg, 1995, 80 (2) : 285.