Late Hypothermia for Hypoxic-Ischemic Encephalopathy

Inclusion Criteria: * Infants born at 36 0/7ths weeks gestational age or greater (by best obstetrical estimate) * Postnatal age between 6 and 24 hours following birth * Infants with a high probability of acute hemodynamic compromise, such as those with: * An acute perinatal event (abruptio placenta, cord prolapse, severe FHR abnormality) * An Apgar score ≤ 5 at 10 minutes * Continued need for ventilation initiated at birth for at least 10 minutes * Cord pH or first postnatal blood gas pH at ≤ 1 hour of ≤ 7.0 * Base deficit on cord gas or first postnatal blood gas at ≤ 1 hour of ≥ 16 mEq/L * Infants matching the above criteria who also have an abnormal neurological exam showing the presence of moderate or severe encephalopathy * Infants whose parents/legal guardians have provided consent for enrollment. NOTE: These inclusion criteria are identical to the NICHD Neonatal Research Network's 2005 Hypothermia study (see links below), except for the time of entry (6-24 hours vs. \< 6 hours of age). Exclusion Criteria: * Any infant with a core body temperature (axilla, rectal) less than 34.0°C for greater than 1 hour * Presence of a known anomaly or chromosomal aberration * Birth weight \< 1,800 grams * Infant in extremis * Infants whose parents/legal guardians or attending physician refuse consent