BACKGROUND: The effects of subclinical histologic chorioamnionitis (HCA) on the newborn infant is a major and still controversial topic in neonatology. The purpose of the present study was to assess the relations between HCA, clinical signs of chorioamnionitis, and neonatal outcomes.

SUBJECTS: 222 consecutively born infants, free of known congenital abnormalities (M 109, F 113, gestational age, M ± SD, 36.5 ± 4.9 wks; birth weight 2591 ± 991 gr).

METHODS: Clinical signs of chorioamnionitis, placental histology and neonatal outcomes were evaluated. The infants were divided into three groups, on the basis of the clinical and histologic findings: A) clinical HCA, B) subclinical HCA, C) HCA-negative. The χ2 statistics. Fisher's test. Mann-Whitney's U. Kruskal-Wallis analysis of variance or Dunn's test were used to evaluate differences between the groups. A p value< 0.05 was considered of statistical significance.

RESULTS: 35 infants (M 15, F 20) were assigned to group A, 52 (M 29, F 23) to B. and 135 (M65, F70) to C. respectively. Differences between the groups concerned: preterm birth (A 68.6%, B 40.3%, C 29.6%. p 0.001; A vs B, p<0.001), birth asphyxia (73.5% 52% 31.9% p 0.001), respiratoory distress syndrome (40% 38.55 7.4% p<0.001), air-leak (5.9% 14.0% 1.5% p<0.01), intraventricular haemorrhage (17.1% 17.3% 0.7% p<0.001), early-onset sepsis (11.4% 5.8% 0& p<0.001), late-nset infection (5.7% 3.8% 0% p<0.05), bronchopulmonary dysplasia (5.7% 9.6% 0% p<0.001), illness severity (SNAP-PE median 26.9, range 0-95; 22.8, 0-82, 7.5, 0-32; p 0.001), therapeutic intensity (NTISS: median 19.63, range 1-42; 15 3, 0-42, 7.4, 0-32; p 0.001), and neonatal mortality (8.6% 15.4% 0% p<0.001).

CONCLUSION: The findings primarily indicate that subclinical HCA is frequent and is associated with adverse perinatal and neonatal outcomes comparable to those of symptomatic HCA