Interleukin-6 and N-terminal pro-brain natriuretic peptide cord blood levels in premature infants: correlations with perinatal variables.

BACKGROUND

Elevated cord blood levels of interleukin-6 and N-terminal pro-brain natriuretic peptide were associated with neonatal complications; however, simultaneously obtained values have not been compared to date.

OBJECTIVES

To study the association of cord blood levels of IL-6 and NT-proBNP with perinatal variables of premature infants and examine the relationship between the obtained values.

METHODS

Cord blood IL-6 (89 samples) and NT-proBNP (66 samples) levels obtained from infants delivered before 32 weeks of gestation were analyzed for associations with perinatal variables and possible correlation between both samples.

RESULTS

Lower gestational age, no antenatal exogenous steroids, low Apgar scores at 1 minute and delivery at a high birth order, were all associated with more infants having elevated IL-6 levels (P = 0.02, P = 0.03, P = 0.03 and P = 0.001, respectively). None of the infants with necrotizing enterocolitis (n=6) had high IL-6 levels (P = 0.01). Increased NT-proBNP levels were associated with low Apgar scores at 1 minute (P = 0.01) and the presence of clinical chorioamnionitis (P = 0.06). Controlling for gestational age, a weak positive correlation was demonstrated between IL-6 and NT-proBNP levels in infants of 24-27 weeks gestational age (R2 = 0.151, P = 0.08), but not among the more mature infants.

CONCLUSIONS

Although both IL-6 and NT-proBNP values were significantly associated with low I minute Apgar scores, our results do not support utilization of these cord blood levels as the sole tool to predict neonatal outcome.