The "brain-sparing" effect: antenatal cerebral Doppler findings in relation to neurologic outcome in very preterm infants.

Abstract

Our purpose was to study the relationship between fetal cerebral circulation and neurologic outcome. In 117 high-risk fetuses (gestational age 25 to 33 weeks) flow velocity waveforms were recorded from the umbilical and medial cerebral arteries. The ratio between umbilical and cerebral pulsatility indexes was calculated. A ratio above a predefined tolerance limit was used as an index for the "brain-sparing" effect. Neonatal neurosonography and neurologic examination were used as outcome parameters. Antenatally raised ratios are associated with poor obstetric outcome (fetal death and fetal growth retardation). The incidence of intracranial hemorrhages and ischemic lesions was not different for infants with a normal or raised prenatal ratio. The incidence of neurologic abnormalities was the same for both ratio groups. The "brain-sparing" effect is a mechanism to prevent fetal brain hypoxia rather than a sign of impending brain damage.