Third-trimester maternal glucose levels from diurnal profiles in nondiabetic pregnancies: correlation with sonographic parameters of fetal growth.

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.