5Shaffer BL, Cheng YW, Vargas JE, et al. Manual rotation of the fetal occiput: predictors of success and delivery [ J ] . Am J Obstet Gynecol, 2006, 194 (5) : e7 -e9.
6Parantainen J, Palomltki O, Talola N, et al. Clinical and sonographic risk factors and complications of shoulder dystocia-a case-control study with parity and gestational age matched controls [J].Eur J Obstct Gynecol Reprod Biol,2014,177 (49) : 110 - 114.