Neonatal Morbidities Associated with Histologic Chorioamnionitis Defined Based on the Site and Extent of Inflammation in Very Low Birth Weight Infants

Conflicting results on the influences of histologic chorioamnionitis (HC) on neonatal morbidities might be partly originated from using different definition of HC. The aim of this study was to determine the relationship between HC and neonatal morbidities using definition of HC that reflects the site and extent of inflammation. This was a retrospective cohort study of 261 very low birth weight (VLBW) infants admitted at a tertiary academic center. Based on the site of inflammation, HC was categorized: any HC; amnionitis; funisitis; amnionitis+funisitis. The extent of inflammation in each site was reflected by sub-defining high grade (HG). The incidences of morbidities in infants with and without HC were compared. The bronchopulmonary dysplasia (BPD) rate was significantly higher in infants with amnionitis and the severe retinopathy of prematurity (ROP) rate was significantly higher in infants with any HC and funisitis. After adjustment for both gestational age and birth weight, the respiratory distress syndrome (RDS) rate was significantly lower in infants with all categories of HC except for HG amnionitis and HG funisitis, which are not associated with lower RDS rate. HG amnionitis was significantly associated with increased BPD rate but the association of HC with severe ROP disappeared. In conclusion, HC is significantly associated with decreased RDS and HG amnionitis with increased BPD while lacking association with other neonatal morbidities in VLBW infants. The association with HC and neonatal morbidities differs by the site and extent of chorioamnionitis.