Chorioamnionitis and brain injury

Article Outline

• Copyright

The association between histologic indicators of inflammation in the fetal membranes (chorioamnionitis) and neurodevelopmental outcomes has been explored in a number of studies with inconsistent results. In animal models, fetal exposure to maternal inflammation, chorioamnionitis, or endotoxin can cause brain lesions similar to those seen in infants with cerebral palsy and poor neurodevelopmental outcomes. In this issue of The Journal, Reiman et al report that placental inflammation associated with the birth of very preterm infants was not related to brain lesions detected by ultrasound or MRI at term or to changes in regional brain volumes. This negative study should send investigators in the field back to the drawing board. Brain lesions and poor neurodevelopmental outcomes increase as gestational age decreases because of multiple antenatal and postnatal factors, and this study suggests that the contribution of histologic chorioamnionitis is not large. A problem is that histologic chorioamnionitis at delivery provides no information about the cause, duration, or intensity of the inflammation or if there is fetal involvement. Chorioamnionitis correlates with a decrease in respiratory distress syndrome but an increase in bronchopulmonary dysplasia, for example. One outcome (decrease RDS) may improve outcomes and the other (increased BPD) may increase brain injury. Fetal responses to inflammation are complex and will depend on the variables of the exposures – inflammation that is generally not available. Future studies of clinical associations between chorioamnionitis and brain injuries will need better definitions of the fetal exposure to inflammation.