This study aimed to assess the effect of GDM on the lactoferrin (LF), secretory immunoglobulin A (SIgA), immunoglobulin G (IgG), and immunoglobulin M (IgM) concentrations in early colostrum, colostrum, and transitional milk samples of hyperglycemic (<i>n</i> = 53) and normoglycemic (<i>n</i> = 49) mothers using enzyme-linked immunosorbent assay (ELISA). The gene discussed is LTF; the disease is gestational diabetes.