Delta neutrophil index (DNI) as a potential biomarker for fetal growth restriction: insights from maternal hematological changes and neonatal outcomes

Abstract

Background This study investigates the role of Delta Neutrophil Index (DNI), an inflammation marker, in late-onset fetal growth restriction (LO-FGR) and its prediction of composite adverse neonatal outcomes. Methods A retrospective study was conducted on 684 pregnant women (456 with normal fetal development and 228 with LO-FGR) who delivered at Health Sciences University Etlik Zubeyde Hanim Women’s Health Training and Research Hospital between January 1, 2015, and June 30, 2018. Composite adverse neonatal outcomes were defined as at least one of the following: 5th minute APGAR score < 7, respiratory distress syndrome (RDS), or neonatal intensive care unit (NICU) admission. Results The FGR group had significantly higher levels of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), monocyte to lymphocyte ratio (MLR), and DNI compared to controls ( p < 0.05, for all). For FGR diagnosis, the DNI demonstrated the highest area under the curve (AUC = 0.677, 95% CI: 0.642–0.711) with a cut-off value of > -2.9, yielding a sensitivity of 78.41%, a specificity of 52.97%, a positive likelihood ratio (+ LR) of 1.68, and a negative likelihood ratio (-LR) of 0.37 ( p < 0.001). For predicting composite adverse neonatal outcomes in the FGR group, DNI again demonstrated superior performance with an AUC of 0.635 (95% CI: 0.598–0.670), a cut-off value of > -2.2, a sensitivity of 69.90%, a specificity of 55.36%, a + LR of 1.56, and a -LR of 0.51 ( p < 0.001). NLR, PLR, and MLR had AUCs below 0.55, indicating poor discriminative ability, with none reaching statistical significance. Conclusion This study highlights the potential role of DNI as a promising biomarker for detecting inflammatory processes associated with LO-FGR and its complications.