The White classification is a system of alphabetically designated categories of diabetes in pregnancy based on age at onset, duration of disease, and the presence or absence of vascular complications. The original classification system underwent several revisions, each progressively increasing in detail and complexity. Individual authors and institutions have modified the classes, resulting in identically lettered classes having different definitions. Some publications make reference to the class of diabetes by letter without providing a reference defining that class. Despite a 1994 American College of Obstetricians and Gynecologists Bulletin, which suggested that the White classification system was less helpful, publications still appear using lettered designations with and without modifications and with and without attendant definitions of terms. A clinically useful system of disease classification should consist of clearly defined, mutually exclusive, easily remembered categories. The current American Diabetes Association classification of diabetes fulfills these requirements and is applicable to diabetes during pregnancy. Adoption of such a system by the obstetrics community in verbal and written medical communication will likely enhance patient care and facilitate accurate data collection and comparison.