Subclinical Histologic Chorioamnionitis and Related Clinical and Laboratory Parameters in Preterm Deliveries

Background: Histologic chorioamnionitis (HCA) is associated with preterm delivery and with neonatal morbidity and mortality. Because HCA is usually subclinical, histologic examination of the placenta is essential for confirmatory diagnosis. In the present study, the correlations between subclinical HCA and relevant clinical and laboratory parameters were analyzed. Methods: This was a retrospective study. We reviewed the placental histopathologic findings and the charts of patients who were admitted to our neonatal intensive care unit after delivery and their mothers between January 2007 and March 2008. A total of 77 preterm infants [gastational age (GA): 32.2 +/- 3.4 weeks, birth weight (BW): 1,718 +/- 554 g] were categorized as group A with histologic evidence of placental inflammation (n=27) or group B without histologic evidence of placental inflammation (n=50). Placental histology was studied to identify the presence of inflammatory states such as chorioamnionitis, funisitis and deciduitis. Laboratory parameters including complete blood count, differential count, and C-reactive protein (CRP) level of mothers and initial arterial blood gas, glucose level and mean blood pressure of the infants were documented. Gestational age, Apgar score, history of prolonged premature rupture of membrane (prolonged PROM), gestational diabetes mellitus, meconium-stained amniotic fluid, pregnancy-induced hypertension and signs of pre-eclampsia were also collected as clinical parameters. All data were analyzed using independent t tests and Fisher's exact test, as appropriate. Results: Group A newborns had a significantly lower gestational age (30.8 +/- 4.1 weeks vs. 33.0 +/- 2.6 weeks, p < 0.05) and higher CRP level (0.56 +/- 0.92 mg/dL vs. 0.12 +/- 0.14 mg/dL, p < 0.05), together with higher maternal WBC count (13,002 +/- 4,344/mu L vs. 10,850 +/- 3,722/mu L, p < 0.05) and higher rate of prolonged PROM [14/27 (51.85%) vs. 8/37 (21.62%), p < 0.05] compared with group B newborns. Conclusion: We found that HCA was significantly correlated with lower gestational age, higher CRP level of preterm infants, higher maternal WBC count, and a higher rate of prolonged PROM. Our results demonstrate a significant association between HCA with an elevated CRP level in preterm infants. These findings further confirmed the association between maternal inflammation and preterm deliveries.