Reference values for C-reactive protein and procalcitonin at term pregnancy and in the early postnatal period

Background: Early recognition of sepsis and prompt treatment improves patient outcome. C-reactive protein is a sensitive marker for tissue damage and inflammation, but procalcitonin has greater specificity for bacterial infection. Limited research exists regarding the use of C-reactive protein and procalcitonin at term pregnancy and the immediate postpartum period. Aim: This study sought to define reference values for C-reactive protein and procalcitonin at term and the early postnatal period. Methods: A prospective cross-sectional study was performed in a university teaching hospital. Venous blood was collected from healthy women (n = 196), aged between 19 and 45 years with an uncomplicated singleton pregnancy, at term (37–40 weeks’ gestation) and on day 1 and day 3 postpartum for the measurement of C-reactive protein and procalcitonin. Results: The reference population comprised of 189 participants: term pregnancy (n = 51), postpartum day 1 vaginal delivery (n = 70) and caesarean section (n = 38) and day 3 (caesarean section, n = 30). The maximum procalcitonin value at term pregnancy was 0.1 μg/L. On day 1 postpartum, 90% and 86.8% of procalcitonin results for vaginal delivery and caesarean section, respectively, were below the decision-threshold of 0.25 μg/L. The specificity of procalcitonin to rule out infection in the reference population was 91.5%. Conclusions: Reference values for procalcitonin were established in a well-characterized population of healthy pregnant women at term and immediately postpartum. The variability of C-reactive protein limits its clinical utility in the assessment of systemic sepsis. Application of the procalcitonin cut-off of 0.25 μg/L in this population will be a valuable adjunct to clinicians ruling out infection in pregnancy and postpartum.