Brain Injury Caused by Activation of the Immune System

We address the role of the immune system in fetal and neonatal brain injury subtypes, including encephalopathy of prematurity (EoP), intraventricular hemorrhage (IVH), neonatal encephalopathy (NE), fetal growth restriction (FGR), perinatal stroke, and maternal immune disorders. We discuss the causes of immune system activation, including infection, sterile inflammation, genetics, and the role of sex. We consider the “compartments” of the immune system: maternal, placental, fetal systemic, and fetal brain. We intersperse the discussions with the impact of stage of development on outcomes and the concepts of acute, secondary, and tertiary phases of injury. The innate cells are addressed, such as innate lymphoid and natural killer cells, granulocytes, microglia, macroglia, macrophages plus the complement system and the adaptive immune lymphocyte subtypes.