Statistics: Independent and joint effects of various clinical factors on the development of significant hyperbilirubinemia will be evaluated by logistic regression analysis Cluster analysis and Chi-squared Automatic Interaction Detection (CHAID) tree method will be used to develop the strategy. At each step, CHAID chooses the independent (predictor) variable that has the strongest interaction with the dependent variable. Categories of each predictor are merged if they are not significantly different with respect to the dependent variable.