Dynamic changes in the middle cerebral artery perfusion in normal full-term human fetuses in relation to the timing of behavioral state

Our aim is to evaluate serial changes in normal full-term fetal cerebral ci rculation according to the behavioral states. Flow velocity waveforms in th e middle cerebral artery and fetal heart rate (FHR) were well recorded in t en of 19 cases by pulsed Doppler ultrasonography and actocardiography over 45 min, respectively. Behavioral states were classified as resting or activ e phase by FHR patterns. Resistance indices (Rls) were calculated every 5 s as an average of two consecutive waveforms. and median RI was chosen in ea ch 2-min segment. In order to evaluate changes in median RI from active-to- resting transition to resting-to-active one statistically, differences in R I between two 2-min segments were examined using Mann-Whitney U-test. As a result: median RI was decreased to the minimum one in the active-to-resting transition for 12 min in all cases: significant decrease to the 2-min segm ent with the minimum one (P < 0.01). Various types of increase to the maxim um median RI during resting phase followed the minimum one: significant inc rease from the 2-min segment with the minimum one to that with the maximum one in all cases (P < 0.001 in eight cases, P < 0.01 in two cases). Thereaf ter, median RI was decreased from the end of resting phase in the resting-t o-active transition for 12 min in all cases: significant decrease from the last 2-min segment of resting phase in all cases (P < 0.01). We reveal that fetal cerebral circulation changes dynamically in relation to the timing i n each behavioral stale. (C) 2000 Elsevier Science Ireland Ltd. All rights reserved.