1Tuzovic L, Djelmis J, Ilijic M. Obstetric risk factors associate with placenta previa development:case control study [ J ]. Croat J, 2003,44:728-733.
2Johnson LG, Mueller BA, Daling JR. The relationship of placeta previa and history of induced abortion [ J ]. Int J Gynaecol Obstet, 2003,81:191-198.
3Faiz AS, Ananth CV. Etiology and risk factors for placenta previa: an overview and meta analysis of observational studies [ J ]. Matem Fatel Neonatal Med, 2003, 13 : 175-190.
4Gilliam M, Rosenberg D, Davis F. The likelihood of placenta previa with greater number of cesare and elireries and higher parity [ J]. Obstet Gynecol,2002 ,99 :976-950.
4Alenear Janior CA, Alencar EC. Influence of prolonged maternal stay in maternal and perinatal outcomes of two series of patients with la- centa previa [ J ]. Rev Bras Ginecol Obsfet ,2012,34 ( 1 ) : 34 - 39.
5Faiz AS, Ananth CV. Etiology and risk factors for placenta prcvia:an overview and meta-analysis of observational studies [ J ]. J Matern Fetal Neonatal Med,2003,13 (3) : 175 - 190.
6Hung TH, Hsien CC, Hsu J J, et al. Risk factors for placenta previa in an Asian population [J]. Int J Gynecol Obstet,2007,97( 1 ) :26.
7Hendrieks MS, Chow YH, Bhagavath B, et al. Previous cesarean sec- tion and abortion as risk factors for developing placenta previa[ J]. J Obstet Gynaecol Res, 1999,25 (2) : 137 - 142.
8Tanimura K, Yamasaki Y, Ebina Y, et al. Prediction of ad- herent placenta in pregnancy with placentaprevia using ul- trasonography and magnetic resonance imaging[J]. Eur J obstet, gynecol and reprod biol, 2015,11 (8): 18741-18744.
9Vinograd A, Wainstock T, Mazor M, et al. A prior placenta accreta is an independent risk factor for post-partum hemorrhage in subsequent gestations[J].Eur J obstet, gynecol and reprod biol, 2015, 11(8): 18720-18724.