OBJECTIVE: We sought to estimate the risk of large for gestational age (LGA) across categories of glucose tolerance. STUDY DESIGN: In a cohort of 89,141 participants, women without gestational diabetes mellitus (GDM) were categorized by their screening and diagnostic test results; those with GDM were categorized as meeting the National Diabetes Data Group or only the American Diabetes Association (ADA) criteria. Multivariable logistic regression models estimated the risk of LGA; screening values 5.5-6.0 mmol/L comprised the referent. RESULTS: In women without GDM, the odds ratio for LGA was 1.89 (95% confidence interval [CI], 1.45-2.45) for fasting, 1.57 (95% CI, 1.31-1.89) for 1-hour, 1.60 (95% CI, 1.33-1.93) for 2-hour, and 1.62 (95% CI, 1.23-2.14) for 3-hour values meeting the ADA time point-specific thresholds. CONCLUSION: For GDM identified in a 2-step procedure, our findings support the use of isolated abnormal fasting values according to the ADA threshold in identifying women who could benefit from treatment.