The adjunctive role of the neutrophil-to-lymphocyte ratio in risk stratification for clinical chorioamnionitis in term pregnancies with meconium-stained amniotic fluid

Objectives To assess the predictive value of the neutrophil-to-lymphocyte ratio (NLR) for clinical chorioamnionitis in term pregnancies complicated by meconium-stained amniotic fluid (MSAF). Methods This retrospective case-control study included women with singleton pregnancies at ≥37 weeks with documented MSAF during labor. The NLR was calculated from maternal blood samples collected at admission. Clinical and hematological parameters were compared between women with and without clinical chorioamnionitis. A multivariable logistic regression model was constructed to identify independent predictors, and a predictive risk score was developed. Results Among 2,014 women with MSAF, 106 (5.3 %) developed clinical chorioamnionitis. Among those with compared to without clinical chorioamnionitis, the mean NLR was higher (5.0 ± 3.8 vs. 4.3 ± 2.3, p = 0.008) and an NLR >3 was more common (85.8 % vs. 76.9 %, p = 0.042). C-reactive protein and white blood cell levels were comparable between the groups. In multivariable analysis, nulliparity (adjusted odds ratio (aOR) 3.087, 95 % confidence interval (CI):1.808–5.273), longer rupture of membranes (aOR 1.092, 95 % CI:1.092–1.189), and NLR (aOR 1.095, 95 % CI:1.025–1.171) were independently associated with clinical chorioamnionitis. A predictive model incorporating nulliparity, rupture of membranes >10 h, and NLR >3 demonstrated an area under the curve of 0.742 (95 % CI: 0.693–0.791, p < 0.001) for predicting clinical chorioamnionitis. Conclusions NLR at admission was independently associated with clinical chorioamnionitis in term pregnancies complicated by MSAF. Incorporating NLR into a predictive model enhanced risk stratification, suggesting that NLR could be a practical biomarker for early identification of increased risk of infection among women with MSAF.