However, their use in this regard is significantly impaired by the evidence that not only bacterial infections, but also several non-infective perinatal circumstances, such as intraventricular hemorrhage, perinatal asphyxia, respiratory distress, hemodynamic instability, and fetal distress, may also raise serum levels of PCT concentrations, making final evaluation very difficult or totally impossible [128,129]. Here, CALCA is linked to bacterial infectious disease.