Gross and Histologic Placental Abnormalities Associated With Neonatal Hypoxic-Ischemic Encephalopathy.

OBJECTIVE: To elucidate particular placental pathology findings that are associated with hypoxic ischemic encephalopathy (HIE) and determine which patterns are associated with adverse fetal/neonatal outcomes. STUDY DESIGN: Multi-institutional retrospective case-control study of newborns with HIE (2002-2022) and controls. Four perinatal pathologists performed gross and histologic evaluation of placentas of cases and controls. RESULTS: A total of 265 placentas of neonates with HIE and 122 controls were examined. Infants with HIE were more likely to have anatomic umbilical cord abnormalities (19.7% vs 7.4%, P = .003), fetal inflammatory response in the setting of amniotic fluid infection (27.7% vs 13.9%, P = .004), and fetal vascular malperfusion (30.6% vs 9.0%, P = <.001) versus controls. Fetal vascular malperfusion with maternal vascular malperfusion was more common in those who died of disease (P = .01). CONCLUSION: Placental pathology examination of neonates with HIE may improve our understanding of this disorder and its adverse outcomes.