Bilirubin, intraventricular hemorrhage, and phenobarbital in very low birth weight babies.

The relationships among serum bilirubin concentration on days 5 and 7, birth weight, the presence of intraventricular hemorrhage, and the receipt of phenobarbital were examined in a group of 232 newborns weighing less than 1,751 g who were intubated, mechanically ventilated by 12 hours after birth, and whose parents had given permission for a randomized trial of phenobarbital prophylaxis of intraventricular hemorrhage. The ratio of serum bilirubin concentration to birth weight (the bilirubin divided by birth weight index [BBI]) was used to examine the impact of 25 variables on a clinical guideline for therapy of hyperbilirubinemia in newborn infants. A linear regression model was used; the most powerful covariate was a birth weight less than 1.0 kg. The only other variable that reduced the BBI was phenobarbital receipt. The presence of intraventricular hemorrhage and ecchymoses had a significant influence increasing the BBI.