Factors predictive of heightened third-day bilirubin levels: a multiple stepwise regression analysis

The purpose of this research was to prospectively study the variables contributing to the variance in third-day bilirubin levels in healthy, full-term newborns. The study subjects were 252 full-term, healthy infants born at the University of Kansas Medical Center over a four-month period. Using a multiple stepwise regression analysis, six factors were found to be significant predictors of higher third-day bilirubin levels: higher cord bilirubin level; lower total serum protein in the infant on admission to the nursery; sex of the child; administration of promethazine hydrochloride during labor; greater weight loss in the infant; and breast-feeding. Several other factors which have been implicated previously--including use of oxytocin for induction or augmentation of labor, previous use of birth control pills by the mother, prolonged rupture of membranes prior to delivery, type of delivery, race, and epidural anesthesia--were not found to be significant predictors of third-day bilirubin levels once the six variables listed had been taken into consideration. The results are discussed in terms of past research as well as implications for clinical practice.