2Witkop CT, Neale D, Wilson LM, et al. Active compared with ex- pectant delivery management in women with gestational diabetes: a systematic review[J]. Obstet Gyneeol, 2009, 113 (1): 206.
3Pildy MD, Clark SL. Shoulder dystocia: risk identification [J]. Clin Obstet Gynecol, 2000, 43 (2): 265.