3[1]Holger KE, Ellice SL, William RC. Regional anesthesia and analgesia for labor and delivery. N Engl J Med,2003,348:319-332.
4[2]Babara LLeighton, Stephen HH. The effects of epidural analgesia on labor, maternal, and neonatal outcomes: A systematic review. Am J Obstet Gynecol,2002,186:S69-77.
5[3]Alexander JM, Sharma SK, McIntire DD, et al. Epidural analgesia lengthens the Friedman active phase of labor. Obstet Gynecol,2002,100:46-50.
6[4]Zhang J, Troendle JF, Yancey MK. Reassessing the labor curve. Am J Obstet Gynecol,2002,187:824-828.
7[7]Theodore RM,David MK. Labor pain management in United States: Understanding patterns and the issue of choice. Am J Obstet Gynecol,2002,186:S173-180.
