White's classification system (WCS) was created 60 years ago to identify diabetic (DM) pregnancies at increased risk for perinatal morbidity and mortality. Our objective was to assess the association between WCS and adverse pregnancy outcome (APO) in contemporary DM pregnancies. We studied diabetic women with singleton pregnancies who delivered at >20 weeks at a single institution over a 1-year period (2007 to 2008). Perinatal outcomes were compared between WCS groups. APO was defined as any of the following: preterm birth