The relationship between perinatal hypoxia and newborn encephalopathy.

Newborn encephalopathy was observed in 30% of 303 selected high-risk preterm and term newborn infants. The newborn encephalopathy was mild or moderate in 65 children and severe in 27. The predictive significance of newborn encephalopathy to motor and cognitive deficits at 1 year was evident from the incidence of deficits in the children with no encephalopathy (17%), in children with mild or moderate encephalopathy (25%), and in children with severe encephalopathy (55%). The biologic risk factors with a significant association with newborn encephalopathy included severe intrapartum fetal hypoxia, moderate and severe newborn respiratory complications, and major infections. Perinatal hypoxia was associated with, and may have contributed to, 26% of the cases of mild and moderate newborn encephalopathy and 66% of the cases of severe newborn encephalopathy. Fetal and newborn hypoxia occurred with equal frequencies in cases of mild and moderate encephalopathy; however, newborn hypoxia was twice as frequent as fetal hypoxia in cases of severe newborn encephalopathy.