IL6 and systemic inflammatory response syndrome: Fetal inflammatory response syndrome (FIRS) defined as an elevation of either fetal plasma IL-6 or C-reactive protein (CRP) above a specific cutoff value (i.e., IL-6 ≥ 11 pg/mL, CRP ≥ 200 ng/mL) [20,21] is thought as the fetal counterpart of systemic inflammatory response syndrome (SIRS) in adults [22,23].