120 - Unconjugated Hyperbilirubinemia and Chronic Lung Disease in Premature Infants ≤ 29 Weeks Gestational Age

Oxidative injury plays a major role in the development of chronic lung disease (CLD). Increased antioxidant levels may reduce oxidative injury in preterm infants and potentially reduce CLD. Unconjugated bilirubin (UCB) is a naturally occurring potent antioxidant that scavenges free oxygen and peroxyl radicals. However, an association between UCB and CLD has not been well studied in premature infants.

Objective: To determine if unconjugated hyperbilirubinemia is associated with the incidence of chronic lung disease in infants born at ≤ 29 weeks gestational age (GA).

Design/Methods: A prospective nested observational study was performed to include infants born between 24^0/7- 29^0/7 weeks GA and admitted to the Neonatal Intensive Care Unit within 12 hours after birth. Infants with chromosomal disorders, craniofacial malformations, TORCH infection, direct hyperbilirubinemia or moribund condition were excluded. Total serum bilirubin (TSB) was measured twice daily during the first postnatal week and thereafter as clinically indicated. The average TSB over the first 14 days was evaluated. CLD was defined as oxygen dependency at 36 weeks corrected GA.  Statistical analyses were performed using 2-sample t-tests or Wilcoxon rank sum tests for continuous variables and Chi-square test or Fisher’s exact test for categorical variables.

Results: Of 296 infants studied, 76 developed CLD (25%). There were significant differences in GA, birth weight, small for gestational age, gender, Apgar score ≤ 5 at 5 minutes, days on oxygen, days on mechanical ventilation, patent ductus arteriosus, days on parenteral nutrition, days on breast milk, frequency of erythrocyte transfusions, postnatal steroids, and sepsis between the 2 groups (Table 1). There were no significant differences in race, ethnicity, pregnancy-induced hypertension, exposure to antenatal steroids, clinical chorioamnionitis, mode of delivery, incidence of respiratory distress syndrome, and necrotizing enterocolitis between the 2 groups. There were no significant differences in peak TSB and days on phototherapy between the 2 groups (Table 1). There was significant difference in average TSB during the first 14 days with lower average TSB among infants with CLD compared to infants without CLD (Table 1). On regression analyses, average TSB was not associated with CLD (Odds ratio 1.1, 95% CI:0.69-1.78, p = 0.6) after controlling for confounders.

Conclusion(s):

Our findings suggest that unconjugated bilirubin may not be protective against chronic lung disease in ≤ 29 weeks GA infants.