Hypoxic ischemic encephalopathy (HIE) is a form of central nervous system injury resulting from inadequate oxygen delivery to some or all of the brain. The lack of oxygen may damage other organs as well, so the patient may manifest with symptoms other than brain damage. Signs and symptoms are variable and depend on affected brain regions. Clinical features include cognitive dysfunction, seizures, status epilepticus, stroke, coma, a persistent vegetative state, and brain death. Prognosis is dependent on the extent of brain injury, which depends on the duration and severity of the inciting event.

HIE can occur prenatally during various stages of fetal development due to preeclampsia, maternal diabetes with vascular disease, congenital fetal infections, maternal drug / alcohol abuse, severe fetal anemia, cardiac disease, lung malformations, or problems with placental blood flow. HIE may also occur during labor and delivery due to umbilical cord occlusion, torsion, or prolapse, rupture of the placenta or uterus, excessive placental bleeding from the placenta, or abnormal fetal position.