Gestational diabetes mellitus (GDM) is a condition in which high blood sugar levels occur during pregnancy. GDM increases the risk of medical complications during pregnancy which may harm the mother and her baby. Since treating GDM to reduce blood sugar reduces the risk of harm, all pregnant women are screened for GDM using a glucose challenge test (GCT). We think that a diet containing low glycemic index foods could help keep blood sugar levels normal during pregnancy and therefore prevent GDM. Thus, the purpose of this study is to see if a diet containing low glycemic index foods will reduced blood sugar after the GCT and reduce the prevalence of GDM in women at high risk for the development of GDM.