Objective: To determine whether there is a relationship between birthweight and interval between 1-h and 3-h glucose tolerance test (GTT) as well as other factors.
Methods: We performed a retrospective analysis of our computerized diabetes database for the years 1992-1997. Ninety-four women with gestational diabetes fulfilled the inclusion criteria (i.e., singleton gestation, term delivery, absence of medical conditions, and known interval between 1-h and 3-h GTT). They were evaluated based on prepregnancy body mass index (BMI), mean glucose values, interval between diagnostic testing, and gestational age of 3-h GTT.
Results: Subjects with GDM had a mean glucose value of 96.8 mg/dl and average prepregnancy BMI of 29.3 kg/m2. When GDM subjects with and without macrosomic infants were compared, mean glucose values (97.4 vs. 96.6 mg/dl) and mean interval (18.1 vs. 17.0 days) between diagnostic testing did not significantly differ. However, maternal prepregnancy BMI was higher in the group of women who gave birth to macrosomic infants (32.2 vs. 28.22 kg/m2, P = 0.008). Using stepwise multiple regression, maternal prepregnancy BMI was the only variable found to be predictive of macrosomia.
Conclusion: We were unable to show a statistical relationship between interval of diagnostic testing and rate of macrosomia. However, we demonstrated a clear relationship between maternal BMI and infant birthweight.