Objective: To evaluate the effectiveness of fetal abdominal circumference-guided therapy for gestational diabetes (GDM) in an outpatient population characterized by highly-prevalent maternal obesity.Methods: Data for this translational retrospective cohort study come from medical records. Fetal abdominal circumference was assessed by ultrasound in late second trimester, and sex- and gestational age-specific percentiles assigned. Taking fetal abdominal circumference percentile as a marker for adequacy of fetal growth, maternal glucose targets were set accordingly: loose, moderate or tight. Associations between mother's targets and neonatal outcomes (small for gestational age (SGA), large for gestational age (LGA), macrosomia, neonatal intensive care unit (NICU) admission, and neonatal hypoglycemia) were assessed using unconditional logistic regression, controlling for pre-gravid body mass index (BMI) and gestational weight gain.Results: In 419 consecutive pregnancies complicated by GDM, neonatal outcomes compared favorably with previous randomized trials of intensive GDM management. Importantly, adverse outcomes were observed less often than might be expected in an obese GDM population. BMI did not have an independent effect on neonatal outcomes.Conclusions: Ultrasound-guided therapy of GDM, in general clinic use, can limit excess macrosomia and LGA, even in a population with significant maternal obesity.