Figure 4. Schematic representation of the pathogenesis of FIRS after chorioamnionitis.
The initial event is the inflammation and immune response in the amniotic compartment consisting of the amniotic fluid and the organs in contact with the amniotic fluid – amnion/chorion, skin, lung and the GI tract. Immune modulation in the lymphoid organs (thymus, spleen and lymph nodes) and the blood likely occurs via signaling from the amniotic compartment. The injury response in the fetal organs is either due to direct contact (in the amniotic compartment) with the inflammatory products/microorganisms or in distant organs due to immune changes in the blood or lymphatic tissues.