The aim of the study was to identify and evaluate a possible correlation between C-reactive protein (CRP) concentration in maternal blood and the risk of developing fetal inflammatory syndrome (FIRS).The study included 158 infants born at 22-34 weeks of gestation and their mothers. Umbilical cord blood cytokines were evaluated in immunoassay tests and maternal blood was tested for CRP concentration.The period of gestation was significantly shorter in the FIRS group as compared to the control group (29.5 ± 3.1 vs. 32.2 ± 2.4 weeks, p < 0.001). Gestational age was ≤ 30 weeks for 53.8% of the newborns in the FIRS group and 15.8% of the newborns in the control group (p < 0.001). Maternal CRP before, during and after labor was significantly higher in the FIRS group as compared to the control group (p < 0.001). Our study investigated the correlation between CRP in maternal blood and IL-6 concentration during the entire perinatal period (p < 0.001).CRP concentration in the FIRS group was significantly higher than in controls before, during, and after labor. Thus, it seems safe to conclude that changing concentration of inflammatory factors in maternal blood are closely related to FIRS. Elevated CRP in maternal blood might signify a progressing intrauterine infection and herald the development of FIRS.