OBJECTIVE: To assess the 24-h glucose levels in a group of nondiabetic, nonobese pregnant women and to verify the presence of correlations between maternal glucose levels and sonographic parameters of fetal growth. RESEARCH DESIGN AND METHODS: A total of 66 Caucasian nonobese pregnant women with normal glucose challenge tests (GCT) enrolled in the study; from this population, we selected 51 women who delivered term (from 37 to 42 weeks completed) live-born infants without evidence of congenital malformations. The women were requested to have three main meals and to perform daily glucose profiles fortnightly from 28-38 weeks without modifying their lifestyle or following any dietary restriction. All subjects were taught how to monitor their blood glucose by using a reflectance meter. Fetal biometry was evaluated by ultrasound scan according to standard methodology at 22, 28, 32, and 36 weeks of pregnancy. RESULTS: The overall daily mean glucose level during the third trimester was 74.7 +/- 5.2 mg/dl. Daily mean glucose values increased between 28 (71.9 +/- 5.7 mg/dl) and 38 (78.3 +/- 5.4 mg/dl) weeks of pregnancy. We found a significant positive correlation at 28 weeks between 1-h postprandial glucose values and fetal abdominal circumference (AC). At 32 weeks, we documented positive correlations between fetal AC and maternal blood glucose levels 1 h after breakfast, 1 and 2 h after lunch, and 1 and 2 h after dinner. At 36 weeks, there was a positive correlation between fetal AC and 1- and 2-h postprandial blood glucose levels. In addition, there was a negative correlation between head-abdominal circumference ratio and 1-h postprandial blood glucose values. CONCLUSIONS: This longitudinal study first provides a contribution toward the definition of normoglycemia in nondiabetic, nonobese pregnant women; moreover, it reveals significant correlations of postprandial blood glucose levels with the growth of insulin-sensitive fetal tissues and, in particular, between 1-h postprandial blood glucose values and fetal AC.