Sonographic evaluation of fetal growth and body composition in women with different degrees of normal glucose metabolism.

OBJECTIVE

To investigate the maternal demographic and metabolic factors contributing to the growth of fetal lean and fat body mass in women whose degree of glucose intolerance is less than that defining gestational diabetes in comparison with women with normal glucose metabolism.

RESEARCH DESIGN AND METHODS

Longitudinal sonographic examinations of 66 singleton fetuses without anomalies of nonobese mothers with abnormal oral glucose challenge test (GCT) results and without gestational diabetes (group 1) were compared with those of 123 singleton fetuses without anomalies of nonobese mothers with normal GCT values (group 2). Lean body mass measurements included head circumference, femur length, mid-upper arm, and mid-thigh central areas. Fat body mass measurements included the anterior abdominal wall thickness, the subscapular thickness, and the mid-upper arm and mid-thigh subcutaneous areas. All the women performed a 24-h glucose profile on the day preceding the ultrasound scan. Multivariate logistic regression analysis established best-fit equations for fetal sonographic measurements of fat and lean body mass. Independent variables included groups 1 and 2, maternal age, parity, prepregnancy BMI, gestational age, weight gain during pregnancy, fetal sex, and the following averaged 24-h profile maternal capillary blood glucose values: preprandial, 1-h postprandial, and 2-h postprandial.

RESULTS

No difference was found between the two groups with respect to fetal lean body mass parameters; the factors that contributed significantly and most frequently were gestational age and fetal sex (male). With respect to fetal fat body mass, all the measurements were significantly higher in group 1 than in group 2. In all instances, the significantly contributing factors were gestational age and maternal 1-h postprandial glucose values, whereas another frequent contributor was prepregnancy BMI.

CONCLUSIONS

Our study suggests the possibility of using sonographically determined fetal fat and lean mass measurements as indicators of body composition. The assessment of these parameters, achievable in a noninvasive and reproducible fashion in pregnancies complicated by glucose intolerance, might enable the real-time detection of fetal overgrowth and disproportion, thus opening the possibility of exploring interventions to limit fetal fat accretion, birth weight, and potential resulting morbidity.