WAVEFORM AND INDICES IN THE CEREBRAL CIRCULATION

Index	26-30 weeks	40 weeks
Common Carotid Artery PI Internal Carotid Artery PI Middle Cerebral Artery PI S/D ratio RI Mean Velocity Anterior Cerebral Artery RI Posterior Cerebral Artery RI	2.13 ± 0.11 1.63 ± 0.36 2.30 ± 0.48 6.89 ± 1.48 0.93 ± 0.049 5.3 ± 2.3 cm/s 0.83 ± 0.05 0.73 ± 0.05	1.89 ± 0.07 1.31 ± 0.41 1.82 ± 0.38 4.23 ± 0.67 0.68 ± 0.087 11.3 ± 3.1 cm/s 0.79 ± 0.04  0.70 ± 0.06