[文献资料]参考文献

2 ﹒ Iyasu S，Saftlas AK，Rowley DL，et al ． The epidemiology of placenta previa in the United States，1979 through1987 ． AmJ Obstet Gynecol，1993，168 ∶ 1424‐.18 ﹒ Masuzaki H，Miura K，Yoshiura K ． Placental mRNA in maternal plasma and its clinical application to ......