Correlation Between C-Reactive Protein and Procalcitonin in the First Hour of Life: A Newborn Observational Study

Abstract

Early recognition of neonatal infection remains challenging because clinical manifestations may be nonspecific and inflammatory biomarkers undergo dynamic changes during the immediate postnatal period. Procalcitonin (PCT) and C-reactive protein (CRP) are widely investigated as complementary biomarkers of neonatal inflammation; however, their relationship when measured immediately after delivery remains insufficiently characterized. This study aimed to determine the correlation between serum PCT and CRP measured during the first hour of life and to explore differences in these biomarkers according to recorded maternal history of infection and clinical signs of sepsis. A secondary observational study was performed on a cohort of 30 newborns from Al-Noor Private Clinic in Sabratha City. Available variables included sex, maternal history of infection, clinical signs of sepsis, CRP, and PCT concentrations. Because biomarker distributions were right-skewed, Spearman’s rank correlation was used as the primary measure of association, with Pearson correlation and Mann–Whitney U tests performed as complementary analyses. The median CRP concentration was 3.25 mg/L (interquartile range [IQR], 0.63–15.75; range, 0.12–94.0 mg/L), while the median PCT concentration was 0.70 ng/mL (IQR, 0.26–1.35; range, 0.12–18.0 ng/mL). A statistically significant moderate positive correlation was observed between CRP and PCT (Spearman’s ρ = 0.414, P = 0.023; 95% bootstrap confidence interval, 0.037–0.728), with a comparable Pearson correlation (r = 0.410, P = 0.024). Newborns with recorded clinical signs of sepsis had higher median CRP and PCT concentrations than those without clinical signs, although the differences were not statistically significant (CRP, P = 0.143; PCT, P = 0.061). Maternal history of infection was associated with significantly higher CRP concentrations (P = 0.029), whereas the difference in PCT concentrations was not statistically significant (P = 0.290). The CRP and PCT measured during the first hour of life demonstrated a moderate positive correlation, suggesting that these biomarkers may reflect partially overlapping inflammatory responses during the immediate postnatal period. However, correlation alone does not establish neonatal infection or diagnostic accuracy. Given the small sample size and absence of definitive infection outcomes in the available dataset, these findings should be considered exploratory and require confirmation in larger prospective studies incorporating gestational age, birth weight, standardized sampling time, blood-culture results, antibiotic exposure, delivery characteristics, and longitudinal clinical outcomes.