Fetal Growth Restriction and Subsequent Low Grade Fetal Inflammatory Response Are Associated with Early-Onset Neonatal Sepsis in the Context of Early Preterm Sterile Intrauterine Environment

There is no information about whether fetal growth restriction (FGR) is an independent risk factor for low-grade fetal inflammatory response (FIR), and which is more valuable for the prediction of early-onset neonatal sepsis (EONS) between low-grade FIR or fetal inflammatory response syndrome (FIRS) in the context of human early preterm sterile intrauterine environment. We examined FIR (umbilical cord plasma (UCP) CRP concentration at birth) according to the presence or absence of FGR (birth weight < 5th percentile for gestational age (GA)) and EONS in 81 singleton preterm births (GA at delivery: 24.5~33.5 weeks) within 72 h after amniocentesis and with sterile intrauterine environment. A sterile intrauterine environment was defined by the presence of both a sterile amniotic fluid (AF) (AF with both negative culture and MMP-8 < 23 ng/mL) and inflammation-free placenta. Median UCP CRP (ng/mL) was higher in cases with FGR than in those without FGR (63.2 vs. 34.5; p = 0.018), and FGR was an independent risk factor for low-grade FIR (UCP CRP ≥ 52.8 ng/mL) (OR 3.003, 95% CI 1.024–8.812, p = 0.045) after correction for confounders. Notably, low-grade FIR (positive likelihood-ratio (LR) and 95% CI, 2.3969 (1.4141–4.0625); negative-LR and 95% CI, 0.4802 (0.2591–0.8902)), but not FIRS (positive-LR and 95% CI, 2.1071 (0.7526–5.8993); negative-LR and 95% CI, 0.8510 (0.6497–1.1145)), was useful for the identification of EONS. In conclusion, FGR is an independent risk factor for low-grade FIR, and low-grade FIR, but not FIRS, has a value for the identification of EONS in the context of the early preterm sterile intrauterine environment.