Association between oral glucose tolerance test (OGTT) glucose levels and fetal macrosomia in non-diabetic women.

Objectives: Foetal macrosomia is a significant obstetric problem that can lead to serious maternal/neonatal complications. The aim of this study was to determine which of the 75 g oral glucose tolerance test (OGTT) glucose values - fasting, first-hour, or second-hour - most strongly predicts foetal macrosomia in non-diabetic patients.

Methods: This cross-sectional study prospectively screened 1,047 pregnant women who underwent a 75 g OGTT. Women with pregestational or gestational diabetes mellitus (GDM) were excluded from the main analysis. A total of 185 non-diabetic women were included. Among the included patients, those who delivered macrosomic foetuses constituted Group 1 (n=16), while those who delivered normal birth weight infants constituted Group 2 (n=169). Fasting, first-hour, and second-hour glucose values from the 75 g OGTT were compared between the groups.

Results: No statistically significant differences were found between the two groups in terms of demographic variables (p>0.05). The mean fasting glucose values in Groups 1 and 2 were 77.75 and 76.11 mg/dL, respectively (p=0.42), the mean first-hour glucose values were 116.25 and 111.51 mg/dL, respectively (p=0.43), and the mean second-hour glucose values were 104.38 and 95.19 mg/dL, respectively (p=0.04). Receiver operating characteristic (ROC) curve analysis was performed for the second-hour glucose concentration, with an AUC of 0.675, and a threshold of 99.5 mg/dL was established.

Conclusions: The second-hour glucose value of the 75 g OGTT may be a marker for foetal macrosomia in nondiabetic patients. These findings suggest that when the second-hour glucose value exceeds 99.5 mg/dL, foetal macrosomia may develop.