Furthermore, animal studies suggest that the expression patterns of CD5 and CD19 proteins determines the cellular phenotype of the B lymphocyte, that of a B1a or a B1b cell, and that the regulatory regions controlling their expression are epigenetically vulnerable. The investigators will therefore isolate DNA and RNA from both B lymphocyte subpopulations and determine whether epigenetic changes to the regulatory regions of the genes coding for CD5 and CD19 protein expression occur in LBW lymphocyte subpopulations as compared to the lymphocytes from NBW infants.