Acute and Chronic Placental Abnormalities in a Multicenter Cohort of Newborn Infants with Hypoxic-Ischemic Encephalopathy.

OBJECTIVE:To examine the frequency of placental abnormalities in a multicenter cohort of newborn infants with hypoxic-ischemic encephalopathy (HIE) and to determine the association between acuity of placental abnormalities and clinical characteristics of HIE. STUDY DESIGN:Infants born at ≥36 weeks of gestation (n = 500) with moderate or severe HIE were enrolled in the High-dose Erythropoietin for Asphyxia and Encephalopathy Trial. A placental pathologist blinded to clinical information reviewed clinical pathology reports to determine the presence of acute and chronic placental abnormalities using a standard classification system. RESULTS:Complete placental pathologic examination was available for 321 of 500 (64%) trial participants. Placental abnormalities were identified in 273 of 321 (85%) and were more common in infants ≥40 weeks of gestation (93% vs 81%, P = .01). A combination of acute and chronic placental abnormalities (43%) was more common than either acute (20%) or chronic (21%) abnormalities alone. Acute abnormalities included meconium staining of the placenta (41%) and histologic chorioamnionitis (39%). Chronic abnormalities included maternal vascular malperfusion (25%), villitis of unknown etiology (8%), and fetal vascular malperfusion (6%). Infants with chronic placental abnormalities exhibited a greater mean base deficit at birth (-15.9 vs -14.3, P = .049) than those without such abnormalities. Patients with HIE and acute placental lesions had older mean gestational ages (39.1 vs 38.0, P < .001) and greater rates of clinically diagnosed chorioamnionitis (25% vs 2%, P < .001) than those without acute abnormalities. CONCLUSIONS:Combined acute and chronic placental abnormalities were common in this cohort of infants with HIE, underscoring the complex causal pathways of HIE. TRIAL REGISTRATION:ClinicalTrials.gov: NCT02811263.