7Demissie K, Rhoads GG, Smulian JC, et al. Operative vaginal delivery and neonatal and infant adverse outcomes: population based retrospective analysis [ J ]. BMJ, 2004,329 ( 7456 ) : 24 -29.
8Johanson R, Menon V. Soft versus rigid vacuum extractor cups for assisted vaginal delivery [J]. Cochrane Database Syst Rev, 2000, ( 2 ) : CD000446.
9Wen SW, Liu S, Kramer MS, et al. Comparison of maternal and infant outcomes between vacuum extraction and forceps deliveries [J]. Am J Epidemiol, 2001,153(2) :103-107.
