[1] Molina G, Weiser TG, Lipsitz SR,et al. Relationship between cesarean delivery rate and maternal and neonatal mortality[J].JAMA,2015, 314(21):2263. [2] American College of Obstetricians and Gynecologists, Society for Maternal-Fetal Medicine, Caughey AB, et al. Safe prevention of the primary cesarean delivery[J].Am J Obstet Gynecol,2014, 69(3):179-193. [3] 段爱红, 范玲. “GT-4A导乐分娩镇痛工作站”的临床效果观察[J].中华围产医学杂志, 2005, 8(4): 234-237. [4] Revill SI, Robinson JO, Rosen M, et al. The reliability of a linear analogue for evaluating pain [J].Anaesthesia,1976, 31(9):1191. [5] Friedman EA. Primigravid labor; a graphicostatistical analysis [J].Obstet Gynecol,1955, 6(6):567. [6] Zhang J, Landy HJ, Branch DW, et al. Contemporary patterns of spontaneous labor with normal neonatal outcomes [J].Obstet Gynecol,2010, 116(6):1281. [7] Suhitharan T, Pham TPT, Chen H,et al. Investigating analgesic and psychological factors associated with risk of postpartum depression development: a case-control study[J].Neuropsychiatr Dis Treat,2016, 12:1333. [8] 杨玲, 许碧云, 胡娅莉. 产程时限变化的荟萃分析[J].中华妇产科杂志, 2012,47(6):431-435. [9] 范刚启, 钱俐俐, 赵杨, 等. 针刺镇痛机制的多样性及问题分析[J].中国针灸,2013,33(1):92-96. (本文编辑:邓丽萍) [收稿日期] 2017-02-19