1Le Ray C,Fraser W,Rozenberg P,et al.Duration of passive and active phases of the second stage of labour and risk of severe postpartum haemorrhage in low-risk nulliparous women[J].Eur J Obstet Gynecol Reprod Biol,2011,158:167-172.
2Friedman EA.The graphic analysis of labor[J].Am J Obstet Gynecol,1954,68:1568-1575.
4Friedman EA.Labor clinical evaluation and management[M].2nd ed.New York:Appleton-Century-Crofts,1978.
5Zhang J,Troendle J,Mikolajczyk R,et al.The natural history of the normal first stage of labor[J].Obstet Gynecol,2010,115:705-710.
6Zhang J,Landy HJ,Branch DW,et al.Contemporary patterns of spontaneous labor with normal neonatal outcomes[J].Obstet Gynecol,2010,116:1281-1287.
7Suzuki R,Horiuchi S,Ohtsu H.Evaluation of the labor curve in nulliparous Japanese women[J].Am J Obstet Gynecol,2010,203:226.
8Zhang J,Troendle JF,Yancey MK.Reassessing the labor curve in nulliparous women[J].Am J Obstet Gynecol,2002,187:824-828.
9Peisner DB,Rosen MG.Transition from latent to active labor[J].Obstet Gynecol,1986,68:448-451.
10Spong CY,Berghella V,Wenstrom KD,et al.Preventing the first cesarean delivery:summary of a joint Eunice Kennedy Shriver National Institute of Child Health and Human Development,Society for Maternal-Fetal Medicine,and American College of Obstetricians and Gynecologists Workshop [J].Obstet Gynecol,2012,120:1181-1193.