Ion of QQ-plots. Since the distribution of sTREM-1 was positively skewed, their natural log transformed values were used so as to have a normally distributed outcome variable for the multiple regression analysis, which was performedMaterials and Methods Ethics StatementThe study was approved by the Ethical Committee of Ghent University hospital (EC/2009/010). All participants provided oral and written informed consent.Study Design and PopulationWe conducted a prospective cohort study at the Department of Obstetrics and Gynecology of Ghent University Hospital in which 768 pregnant women between 24 and 42 weeks’ gestation, presenting to the labor and delivery ward were enrolled, in order to build a bank of biological samples and clinical data and to explore putative associations between inflammatory markers of term and preterm labor. [24]All subjects for this study were selected from the prospective cohort except patients in group 2 (see below). A convenience sample of 176 singleton pregnancies was selected and divided into four groups according to gestational age (GA) and labor status: (1) women with preterm labor (PTL), whoSerum sTREM-1 in Laboron the full dataset (n = 176). A backward selection procedure was applied in which covariates were sequentially removed in order of increasing significance until only terms with Calciferol site p-value below 0.10 remained. The subgroups were translated into three variables: preterm (vs. at term), labor (vs. not in labor) and rupture of the membranes (ROM)(vs. intact membranes). These variables are considered as key covariates and remained in the model regardless of their significance. Other covariates considered in the model selection were maternal age, educational level, marital status, smoking, body mass index (BMI), history of PTB, storage time and time delay between blood sampling and serum harvesting (further described as sample age). After backward selection of main terms, first order interactions were considered between all 117793 biological activity remaining covariates, yielding the final model. Spearman correlation was performed to estimate correlations between serum concentration of sTREM-1 and the admission-to-delivery interval in the PTB group. All statistical analyses and tests were performed two-sided at the 5 significance level using SPSS statistics 19 software (IBM, Chicago, Illinois).compared to women with higher education and 28 lower in women with a history of PTB versus no history. With other covariates held constant, sTREM-1 concentrations multiplied with a factor 1.004 for every additional hour of sample age.Serum sTREM-1 Concentrations in PPROM vs. PTL and Relation with Admission-to-Delivery IntervalIn the PTB group, no differences in sTREM-1 concentrations were observed between women with PPROM versus women with PTL and intact membranes (372 pg/ml, IQR 303?94 vs. 342 pg/ml, IQR 303?36; P = 0.46). This result did not change when using multiple regression analysis (data not shown). The median admission-to-delivery interval in the PTB group was 3,5 days (IQR 3,5?), in women with PPROM 4 days (IQR 0-7) and 1317923 in women with PTL and intact membranes 3 days (IQR 0?4,5). The concentration of sTREM-1 was not related to the admissionto-delivery interval in women with PTB (r = 0.17, P = 0.23) neither in the subgroups (PPROM: r = 0.30, P = 0.08; PTL and intact membranes: r = -0.11, P = 0.67).Results Demographic and Clinical Characteristics of the Study PopulationDemographic and clinical characteristics of the study population.Ion of QQ-plots. Since the distribution of sTREM-1 was positively skewed, their natural log transformed values were used so as to have a normally distributed outcome variable for the multiple regression analysis, which was performedMaterials and Methods Ethics StatementThe study was approved by the Ethical Committee of Ghent University hospital (EC/2009/010). All participants provided oral and written informed consent.Study Design and PopulationWe conducted a prospective cohort study at the Department of Obstetrics and Gynecology of Ghent University Hospital in which 768 pregnant women between 24 and 42 weeks’ gestation, presenting to the labor and delivery ward were enrolled, in order to build a bank of biological samples and clinical data and to explore putative associations between inflammatory markers of term and preterm labor. [24]All subjects for this study were selected from the prospective cohort except patients in group 2 (see below). A convenience sample of 176 singleton pregnancies was selected and divided into four groups according to gestational age (GA) and labor status: (1) women with preterm labor (PTL), whoSerum sTREM-1 in Laboron the full dataset (n = 176). A backward selection procedure was applied in which covariates were sequentially removed in order of increasing significance until only terms with p-value below 0.10 remained. The subgroups were translated into three variables: preterm (vs. at term), labor (vs. not in labor) and rupture of the membranes (ROM)(vs. intact membranes). These variables are considered as key covariates and remained in the model regardless of their significance. Other covariates considered in the model selection were maternal age, educational level, marital status, smoking, body mass index (BMI), history of PTB, storage time and time delay between blood sampling and serum harvesting (further described as sample age). After backward selection of main terms, first order interactions were considered between all remaining covariates, yielding the final model. Spearman correlation was performed to estimate correlations between serum concentration of sTREM-1 and the admission-to-delivery interval in the PTB group. All statistical analyses and tests were performed two-sided at the 5 significance level using SPSS statistics 19 software (IBM, Chicago, Illinois).compared to women with higher education and 28 lower in women with a history of PTB versus no history. With other covariates held constant, sTREM-1 concentrations multiplied with a factor 1.004 for every additional hour of sample age.Serum sTREM-1 Concentrations in PPROM vs. PTL and Relation with Admission-to-Delivery IntervalIn the PTB group, no differences in sTREM-1 concentrations were observed between women with PPROM versus women with PTL and intact membranes (372 pg/ml, IQR 303?94 vs. 342 pg/ml, IQR 303?36; P = 0.46). This result did not change when using multiple regression analysis (data not shown). The median admission-to-delivery interval in the PTB group was 3,5 days (IQR 3,5?), in women with PPROM 4 days (IQR 0-7) and 1317923 in women with PTL and intact membranes 3 days (IQR 0?4,5). The concentration of sTREM-1 was not related to the admissionto-delivery interval in women with PTB (r = 0.17, P = 0.23) neither in the subgroups (PPROM: r = 0.30, P = 0.08; PTL and intact membranes: r = -0.11, P = 0.67).Results Demographic and Clinical Characteristics of the Study PopulationDemographic and clinical characteristics of the study population.