The importance of intra-amniotic inflammation in the subsequent development of atypical chronic lung disease

Objective. To examine whether the intra-amniotic inflammation is a risk factor for the development of atypical chronic lung disease (CLD). Study design. A retrospective cohort study was undertaken in 72 patients who delivered preterm neonates (gestational age: 24-32 weeks) within 5 days of amniocentesis and whose neonates subsequently developed CLD. Atypical CLD was defined as CLD without respiratory distress syndrome (RDS). Intra-amniotic inflammation was defined as an elevated amniotic fluid (AF) concentration of matrix metalloproteinase-8 (MMP-8) (>23 ng/ml). Results. (1) Atypical CLD was identified in 54.2% (39/72) of cases with CLD; (2) there were no significant differences in the median gestational age at birth and the rate of antenatal corticosteroid use between infants with atypical CLD and CLD with RDS; (3) preterm newborns with atypical CLD had a significantly higher median AF MMP-8 concentration (median 373.1 ng/ml vs. 8.6 ng/ml, p=0.003) and median AF white blood cell count (median 450.0/mm(3) vs. 5.5/mm(3), p=0.009), and a higher rate of intra-amniotic inflammation (74.4% vs. 45.5%, p=0.012) than those with CLD with RDS. Conclusion. Intra-amniotic inflammation confers a greater risk for atypical CLD than for typical CLD with initial RDS. This novel observation strengthens the importance of prenatal inflammation as a mechanism of lung injury.