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 (HEAL) 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 321/500 (64%) trial participants. Placental abnormalities were identified in 273/321 (85%) and were more common in infants ≥ 40 weeks of gestation (93% vs. 81%, p=0.01). 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=0.049) than those without such abnormalities. Patients with HIE and acute placental lesions had older mean gestational ages (39.1 vs. 38.0, p<0.001) and higher rates of clinically diagnosed chorioamnionitis (25% vs 2%, P < .001) than those without acute abnormalities. CONCLUSION Combined acute and chronic placental abnormalities were common in this cohort of infants with HIE, underscoring the complex causal pathways of HIE.