Gestational diabetes mellitus and maternal overweight and obesity are associated with increased risk for adverse maternal and perinatal outcomes, such as fetal overgrowth. Although most studies addressing the effects of maternal BMI on adverse outcomes include women with GDM, a little is known about associations between maternal BMI and fetal metabolic status evaluated by ultrasonography means. One of the ultrasound parameter of glycemic controlis the measurement of fetal liver length. Prospective study of 385 women with monofetal pregnancies and established risk for GDM underwent mid-trimester ultrasound exam, during which fetal liver length were measured. After exam, body mass index (BMI) was determined for each patient. Each participant underwent 100 g fasting oral glucose challenge test (oGTT) in order to confirm or to exclude diagnosis of GDM. There was a statistically highly significant positive correlation between the BMI and fetal liver length for the entire sample (N=385; p<0.001; R=+0.55) as well in the sample of GDM patients (N=96; p<0.001; R=+0.58) and controls (N=289; p<0.001; R=+0.33). Maternal BMI has impact on fetal liver length assessed by ultrasound exam. This influence is even higher in GDM.