Fasting Plasma Glucose and Glycosylated Plasma Protein at 24 to 28 Weeks of Gestation Predict Macrosomia in the General Obstetric Population

ABSTRACT

The purpose of this study was to modify the traditional gestational diabetes screening process in order to provide a test that might more reliably detect those women at risk of delivering a macrosomic infant despite a negative test for gestational diabetes mellitus (GDM). Pregnant women (n = 160) were screened for GDM at 24 to 28 weeks' gestation using the traditional 50 g glucose challenge test (GCT). In addition, glycosylated hemoglobin, glycosylated serum protein, and glycosylated plasma protein (GPP) were analyzed from blood drawn atthis same time. If the patient's challenge test was positive (140 mg/dL or higher), a 100 g oral glucose tolerance test (OGTT) was performed. Twenty-three women had a positive GCT (14.4%) and five (3.13%) were excluded from further study because they received treatment for gestational diabetes based on a positive OGTT. None of the GCT-negative or the GCT-positive-OGTT-negative patients received treatment. Gestational age at delivery, infant gender, and birthweightwere retrieved from birth records. Although several correlations with infant birthweight were found, the fasting plasma glucose (FPG) and GPPs proved most significant. The FPG on the OGTT significantly correlated with infant birthweight (p <0.001; r = 0.94). A value greater than 90 mg/dL proved to be 100% sensitive and 64% specific for infant birthweight more than 4000 g. The relationship of the GPP and subsequent infant birthweight was also significant (p <0.001; r = 0.81). A GPP greater than 23% proved to be 100% sensitive in predicting birthweight above 4000 g (11 of 11 infants); however, the test had a 52% specificity. Partial correlation coefficients that take into account the interdependence of response revealed that each independently predicted infant birthweight. Using a combination of a GPP above 23% and a FPG above 90 mg/dL resulted in 100% sensitivity and 93% specificity for an infant greater than 4000 g. This study indicates that women at risk for delivery of a macrosomic infant may be identified at 24 to 28 weeks' gestation by measurement of FPG and GPP.

Keywords

Gestational diabetes mellitus - screening - macrosomia - fasting plasma glucose - glycosylated plasma proteins