Contribution of Fetal Inflammatory Response Syndrome (FIRS) with or without Maternal-Fetal Inflammation in The Placenta to Increased Risk of Respiratory and Other Complications in Preterm Neonates

This study classifies fetal inflammatory response syndrome (FIRS) based on the presence or absence of maternal-fetal inflammation in the placenta and clarifies the association of FIRS with neonatal morbidities. Women (330) who delivered at gestational ages of 22w0d-33w6d were enrolled and grouped into four based on FIRS and maternal/fetal inflammatory response (MIR/FIR) statuses: Group A: without FIRS and MIR/FIR (reference group); Group B: MIR/FIR alone; Group C: FIRS and MIR/FIR; and Group D: FIRS without MIR/FIR. The associations between bronchopulmonary dysplasia (BPD), adverse neonatal outcomes, extremely low gestational age and Groups B, C, and D were investigated after adjustment for potential confounders. Among patients with FIRS, 29% were in Group D. The risk of BPD was increased in Groups C (adjusted odds ratio (aOR): 3.36; 95% confidence interval (CI): 1.14–9.89) and D (aOR: 4.17; 95% CI: 1.03–16.9), as was the risk of adverse neonatal outcomes (Group C: aOR: 7.17; 95% CI: 2.56–20.1; Group D: aOR: 6.84; 95% CI: 1.85–25.2). The risk of extremely low gestational age was increased in Group D (aOR: 3.85; 95% CI: 1.56–9.52). Therefore, FIRS without MIR/FIR is not rare and may be associated with neonatal morbidities more than FIRS and MIR/FIR.