The objective of this study is to determine the change of C-reactive protein (CRP) levels in the peripheral blood of preterm infants at birth according to the stage of intrauterine inflammation.

A total of 187 infants (<32 weeks of gestation) were divided into a "no histologic chorioamnionitis" [HCAM (-), n=85] group and a "histologic chorioamnionitis" [HCAM (+), n=102] group according to placental pathologic findings. Furthermore, the HCAM (+) group was subdivided into a "funisitis" [F (+), n=49] group and a "no funisitis" [F (-), n=53] group and also into a "funisitis/amnionitis" [FA (+), n=58] group and an "isolated chorio-deciduitis" [FA (-), n=44] group. High-sensitivity CRP levels in the peripheral blood at birth were measured.

Peripheral blood CRP levels were significantly higher in the HCAM (+), F (+), F (-), and FA (+) groups than in the HCAM (-) group, but were not significantly different between the FA (-) and HCAM (-) groups. In addition, peripheral blood CRP levels were significantly higher in the F (+) and FA (+) groups than in the F (-) and FA (-) groups, respectively. For identification of amnionitis or funisitis, a cut-off value of 0.02 mg/dL was chosen. Clinical chorioamnionitis, proven early onset sepsis, histologic chorioamnionitis, and funisitis had higher incidences in infants with peripheral blood CRP levels higher than 0.02 mg/dL.

The present study shows that peripheral blood CRP levels at birth in preterm infants born before 32 weeks' gestation is significantly increased in amnionitis or funisitis and might reflect the progress of histologic chorioamnionitis.