Identifying the pregnancy at risk for intrauterine growth retardation: Possible usefulness of the intravenous glucose tolerance test

Antenatal detection of intrauterine growth retardation (IUGR) remains problematic. Previous animal and human studies have documented a relationship between increased substrate delivery to the fetus, e.g., in diabetes mellitus, and the birth of large-for-gestational age infants. The purpose of the study of 55 pregnancies, in which intravenous glucose tolerance tests (IVGTTs) were performed during the third trimester, was to examine the hypothesis that evidence of decreased availability of substrates for fetal growth precedes the birth of small-for-gestational age (SGA) infants; hence, the IVGTT might be useful for the detection of pregnancies complicated by IUGR. Increased glucose utilization rates (kt) and 10-minute plasma glucose concentrations and decreased plasma glucose concentrations at fasting and 60 minutes were found to be significantly associated with decreased infant birth weight, adjusted for gestational age. The kt and 10- and 60-minute glucose values together could account for 40% of the variance in age-adjusted birth weight (r = 0.63, p < 0.01). The IVGTTs in the pregnancies resulting in the birth of SGA infants were characterized by kt > 2 and plasma glucose levels at fasting of < 64 mg/dl, at 10 minutes of > 193 mg/dl, and at 60 minutes of < 82 mg/dl. When the kt was > 2, six (30%) of 20 infants were SGA; when the kt was ≤ 2, none (0%) of the 35 infants was SGA. These results suggest that, regardless of the underlying reason for the association, parameters of maternal glucose metabolism may be useful in detecting the pregnancy at risk for IUGR.