Neutrophil to Lymphocyte Ratio and Red Blood Cell Distribution Width Levels in Preterm vs. Term Births

Abstract

Objective: Despite its broad etiology, preterm labor has been firmly linked to inflammatory/infectious processes. However, very few cases of preterm birth are preceded by acute signs and symptoms of clinical infection. Many studies have found neutrophil-to-lymphocyte ratio and red blood cell distribution width to be elevated in cases of subclinical infections. We performed a retrospective study to compare the levels of these two markers in preterm vs. term births. Material and methods: Patient information was obtained retrospectively. Preterm and term birth patients were captured from our database during a three-year period. Neutrophil-to-lymphocyte ratio and red blood cell distribution width in the first trimester and on admission to labor and delivery was obtained. A sample size of 130 per group was required to find a 20% difference with 80% power (standard deviation=3.2). p-values less than 0.05 were considered significant. Results: The preterm birth group contained 137 patients with an average gestational age of 32.4 ± 4.1 weeks and the term birth group included 145 patients with an average gestational age of 39.2 ± 1.1 weeks. The neutrophilto- lymphocyte ratio at the time of delivery was found to be higher in the preterm birth group (5.9 ± 5.1 vs. 4.6 ± 3.2, p=0.007). Red blood cell distribution width at delivery did not differ between groups (13.6 ± 0.9, 13.9 ± 1.8, p=0.09). Subgroup analysis of preterm patients with preterm premature rupture of membranes (n=52) or gestational age <35 weeks (n=72) did not result in significant difference when compared to term patients. Conclusion: Neutrophil-to-lymphocyte ratio was significantly elevated in preterm birth patients when compared to term patients. No statistically significant difference in red blood cell distribution width was found between groups.