In this study, serum procalcitonin (PCT) levels in preterm neonates were found to be linked with postnatal respiratory condition severity.

• According to a recent report, elevation of serum PCT levels occurs due to respiratory failure immediately after birth.

• However, the association between biological inflammation markers, such as PCT and C-reactive protein (CRP), and postnatal respiratory condition severity needs to be explored.

• This study included preterm neonates who were grouped based on the received respiratory management: non-respiratory support (NRS), respiratory support (RS), surfactant administration therapy (STA), and STA with nitric oxide inhalation therapy (NO).

• For these respective groups, the observed PCT levels were 1.04, 6.46, 12.93, and 86.79 μg/L, respectively; the CRP levels were 0.40, 0.80, 1.10, and 16.40 mg/L, respectively.

• Significantly lower PCT levels were detected in neonates receiving STA in the birth subgroup (4.82 μg/L) compared to those receiving STA in the admission subgroup (14.71 μg/L).

• In the STA multiple-dose subgroup, significantly higher PCT levels (24.87 μg/L) were found, relative to the STA single-dose subgroup (12.47 μg/L).

• There were no significant differences in the CRP levels.