OBJECTIVE To determine the effects of maternal factors, including prepregnancy maternal adiposity, weight gain during pregnancy, degree of abnormality of the glucose tolerance test, glycemia during pregnancy, and treatment with insulin versus diet therapy, on neonatal body weight, adiposity, and blood pressure in infants of mothers with gestational diabetes (IGDM) and control patients. RESEARCH DESIGN AND METHODS A total of 119 term IGDM, including 57 large-for-gestational-age (LGA) and 62 appropriate-for-gestational-age (AGA) infants, and 143 term control infants, including 74 LGA and 69 AGA infants, were prospectively enrolled. Maternal measurements of prepregnancy weight, height, and weight gain were abstracted from medical records. A diagnosis of gestational diabetes was made on the basis of an initial 1-h 50-g glucose screen value ≥130 mg/dl followed by two abnormal values in a 100-g oral glucose tolerance test. Infant anthropometric measurements were obtained, and blood pressure was measured on day 2 of life. Correlation analyses and multiple regression analyses were performed to assess the relationships among maternal factors and neonatal adiposity and blood pressure. RESULTS Multiple regression analyses to determine the effects of significant maternal factors on infant body mass index (BMI) revealed that prepregnancy weight and weight gain were significant predictors for both IGDM and control infants. An increased glucose screen predicted BMI for control subjects, whereas the mean 2nd and 3rd trimester glucose values were the significant predictors for IGDM. Also, increased newborn triceps skinfold thickness measurements correlated with increased systolic blood pressure for IGDM (r = 0.29, P < 0.03). CONCLUSIONS Increased maternal prepregnancy weight, weight gain in pregnancy, and glycemia in pregnancy all place IGDM at increased risk of macrosomia and adiposity. Increased adiposity in the IGDM appears to be related to increased infant blood pressure. Longitudinal evaluation is needed to determine whether neonatal adiposity in IGDM is predictive of increased adiposity and blood pressure during childhood.