8Hecher K, Campbell S, Doyle P, et al. Assessment of fetal compromise by Doppler ultrasound investigation of the fetal circulation [ J ]. Circulation, 1995,91(1): 129.
9Timmerman E, Clur SA, Pajkrt E, et al. First-trimester measurement of the ductus venosus pulsatility index and the prediction of congenital Heart defects [ J ]. Ultrasound Obstet Gynecol, 2010, 36(6): 668-675.
10Florjahski J, Fuchs T, Zimmer M, et al. The role of ductus venosus Doppler flow in the diagnosis of chromosomal abnormalities during the First trimester of pregnancy [J]. Adv Clin Exp Med, 2013, 22(3): 395-401.