Predictive value of systemic immune-inflammation index in patients with preterm labor

Purpose: The aim of this study was to investigate whether the systemic immune-inflammatory index (SII) could predict the development of preterm labor in pregnant women. Materials and Methods: Pregnant women aged 18 years and over who presented to our clinic with spontaneous labor between January 1, 2018, and December 31, 2021, had intact membranes, and had a single living fetus were retrospectively evaluated. The women were divided into two groups, preterm and term delivery, according to the week of delivery. The clinical and laboratory characteristics of the women were assessed. The patients' platelet-to-lymphocyte ratio (PLR), neutrophil-to-lymphocyte ratio (NLR), and SII (neutrophil count x platelet count/lymphocyte count) were calculated. Results: The study included 171 women with preterm labor and 173 women with healthy term labor. The PLR, NLR, and SII values were statistically significantly higher in the preterm group than in the term group. The multivariate logistic regression analysis showed that SII (odds ratio [OR]: 3.65, 95% confidence interval [CI]: 2.21-10.07) was an independent predictor of the development of preterm labor. We found that the power of SII to predict preterm labor (area under the curve [AUC]: 0.792) was higher than that of NLR (AUC: 0.725) or PLR (AUC: 0.716) alone. SII values higher than 789.3 predicted preterm labor with 68.4% sensitivity and 81.5% specificity. Conclusion: We found that SII was more valuable than NLR and PLR in the early detection of preterm labor. SII can help identify pregnant women at risk of developing preterm labor in the early stages of pregnancy.