Middle cerebral artery blood flow in normal and growth-retarded fetuses.

Doppler ultrasonography of the middle cerebral artery was performed on 17 fetuses that were small for gestational age at the time of delivery. Results were compared with a group of 25 fetuses that had a normal weight for gestational age at the time of delivery. Despite a significant difference in fetal weight and systolic/diastolic ratio of the umbilical artery between the two groups, no difference was found in either the systolic/diastolic ratio or in the Pourcelot index of the middle cerebral artery. This may reflect a protective effect on the brain circulation in the small-for-gestational-age fetus.