In addition to Steve's points, all of which I agree with. Why is BMI categorized? Binning continuous variables causes problems. See Harrell. Have you corrected/noted the problems with BMI? Some of these are summarized in my post on Yahoo (very nontechnical) but there are additional problems when using it with children as good values change with age. Your predictor values seem highly likely to be colinear. You can check this with the COLLIN option in PROC REG (since colinearity is a function only of the predictors, the incorrectness of REG doesn't matter). ... View more