“…Recent reports on Doppler flow recordings from umbilical arteries suggest that this non-invasive technique may provide direct information as to the functional state of the placental villous circulation (McCallum et al, 1978;Stuart et al, 1980;Giles et al, 1983;Reuwer et al, 1984). The method is based on the principle that the pulsatility of arterial flow reflects downstream vascular resistance (Gosling and Ring, 1974;Skidmore et al, 1980).…”