A "multi-hit" model of neonatal white matter injury: Cumulative contributions of chronic placental inflammation, acute fetal inflammation and postnatal inflammatory events

Objective: We sought to determine whether cumulative evidence of perinatal inflammation was associated with increased risk in a "multi-hit" model of neonatal white matter injury (WMI). Methods: This retrospective cohort study included very preterm (gestational ages at delivery <32 weeks) live-born singleton neonates delivered at Hutzel Women's Hospital, Detroit, MI, from 2006 to 2011. Four pathologists blinded to clinical diagnoses and outcomes performed histological examinations according to standardized protocols. Neurosonography was obtained per routine clinical care. The primary indicator of WMI was ventriculomegaly (VE). Neonatal inflammation-initiating illnesses included bacteremia, surgical necrotizing enterocolitis, other infections, and those requiring mechanical ventilation. Results: A total of 425 live-born singleton neonates delivered before the 32^nd week of gestation were included. Newborns delivered of pregnancies affected by chronic chorioamnionitis who had histologic evidence of an acute fetal inflammatory response were at increased risk of VE, unlike those without funisitis, relative to referent newborns without either condition, adjusting for gestational age [odds ratio (OR) 4.7; 95% confidence interval (CI) 1.4-15.8 vs. OR 1.3; 95% CI 0.7-2.6]. Similarly, newborns with funisitis who developed neonatal inflammation-initiating illness were at increased risk of VE, unlike those who did not develop such illness, compared to the referent group without either condition [OR 3.6 (95% CI 1.5-8.3) vs. OR 1.7 (95% CI 0.5-5.5)]. The greater the number of these three types of inflammation documented, the higher the risk of VE (P<0.0001). Conclusion: Chronic placental inflammation, acute fetal inflammation, and neonatal inflammation-initiating illness seem to interact in contributing risk information and/or directly damaging the developing brain of newborns delivered very preterm.