7Chauhan S P, Reynolds D, Cole J. Absent or reversed end-di- astolic flow in theumbilical artery:outcome at a community hospi- tal[J].J Miss State Meal Assoc, 2005, 46(06):163-168.
8Arauz J F, Leon J C, Vela squez P R, et al. Umbilical artery Doppler velocimetry and adverse perinatal outcome in severe pre-eclampsia[J]. Ginecol Obstet Mex, 2008, 76(08):440-449.
9Bonnin P, Fouron J C, Teyssier G, et al. Quantitative assessment of circulatory changes in the fetal aortic isthmns during pro- gressive increase of resistance to umbilical blood flow[J]. Cir- culation, 1993, 88( 1 ):216-222.
10Lee W, Lee V L,Kirk J S, et aI.Vasa prenatal diagnose is, natural evolution, and clinical outcome[J]. Obstet Gynecol, 2000,95:572-576.