Mild to Moderate, but Not Minimal or Severe, Acute Histologic Chorioamnionitis or Intra-Amniotic Inflammation Is Associated with a Decrease in Respiratory Distress Syndrome of Preterm Newborns without Fetal Growth Restriction

Abstract

Background: Acute histologic chorioamnionitis (acute-HCA) is known to be associated with a decreased risk of respiratory distress syndrome (RDS) in newborns. However, there is no information about whether the severity of acute-HCA or intra-amniotic inflammation (IAI) is associated with the development of RDS. Objectives: To assess the relationship between the severity of acute-HCA or IAI and the development of RDS in preterm newborns due to preterm labor and intact membranes (PTL) or preterm premature rupture of membranes (preterm-PROM) without fetal growth restriction (FGR). Methods: The frequency of RDS was examined in 378 singleton preterm neonates (24.5-34 weeks' gestation) due to PTL or preterm-PROM without FGR. Patients were divided into 4 groups according to the severity of acute-HCA (i.e. total grade: minimal, 1; mild, 2; moderate, 3-4; severe, 5-6) or IAI (i.e. amniotic fluid MMP-8: minimal, 23-100 ng/ml; mild, 100-400 ng/ml; moderate, 400-800 ng/ml; severe, ≥800 ng/ml). Amniotic fluid MMP-8 was measured in 196 patients delivered within 7 days of amniocentesis. Results: Mild to moderate, but not minimal or severe, acute-HCA (minimal, 24%; mild, 13%; moderate, 19%; severe, 41%; preterm-reference group, 26%) or IAI (minimal, 24%; mild, 11%; moderate, 17%; severe, 25%; preterm reference group, 23%) was associated with a significant decrease in RDS as compared with the preterm reference group (each for p < 0.05 after the adjustment of gestational age at delivery, antenatal corticosteroid use, newborn gender, cesarean delivery and preterm-PROM as a cause of preterm birth). Conclusions: Mild to moderate, but not minimal or severe, acute-HCA or IAI is associated with a significant decrease in RDS among preterm neonates due to PTL or preterm-PROM without FGR.