The Placenta in Neonatal Encephalopathy: A Case-Control Study

Objective We assessed whether specific histologic placental lesions were associated with risk for neonatal encephalopathy, a strong predictor of death or cerebral palsy. Study design Case-control study of singletons with gestational ages >= 35 weeks. Data were abstracted from a prospectively collected database of consecutive births at a hospital in which placental samples from specified sites are collected and stored for all inborn infants. Placentas of infants with neonatal encephalopathy were compared with randomly selected control infants (ratio of 1:3). Placental histologic slides were read by a single experienced perinatal pathologist unaware of case status, using internationally recommended definitions and terminology. Findings were grouped into inflammatory, maternal, or fetal vascular malperfusion (FVM) and other lesions. Results Placental samples were available for 73 of 87 (84%) cases and 253 of 261 (97%) controls. Delivery complications and gross placental abnormalities were more common in cases, of whom 4 died. Inflammation and maternal vascular malperfusion did not differ, and findings consistent with global FVM were more frequent in case (20%) than control (7%) placentas (P = .001). There was a trend toward more segmental FVM and high-grade FVM (fetal thrombotic vasculopathy) among cases. Some type of FVM was observed in 24% of placentas with neonatal encephalopathy. In infants with both neonatal encephalopathy and placental FVM, more often than in infants with neonatal encephalopathy without FVM, electronic fetal monitoring tracings were considered possibly or definitely abnormal (P = .028). Conclusions Vascular malperfusion of subacute or chronic origin on the fetal side of the placenta was associated with increased risk of neonatal encephalopathy.