The role of umbilical cord thickness and HbA1c levels for the prediction of fetal macrosomia in patients with gestational diabetes mellitus

The aim of this study was to investigate the effects of HbA1c levels and umbilical cord thickness upon birth weight, particularly in pregestational and gestational diabetic patients. Pregnant women were included in the study and were divided into two groups. The first group consisted of patients who were diagnosed with pregestational or gestational diabetes mellitus. The control group consisted of pregnant women who were not diagnosed with pregestational or gestational diabetes mellitus. Ultrasound examination was performed twice. Examinations were performed at 27-28 weeks and 36-37 weeks of gestation, respectively. During ultrasound examinations, fetal anthropometric parameters, biparietal diameter, abdominal circumference, femur length and estimated fetal weight (which was calculated automatically according to Hadlock's formula) were measured. Additionally, the sonographic cross-sectional areas of the umbilical cord, the umbilical arteries and the umbilical vein were measured in a free loop of the umbilical cord, using the software of the ultrasound machine. The cross-sectional area of Wharton's jelly was computed by subtracting the cross-sectional area of the vessels from that of the umbilical cord. HbA1c levels were measured for diabetic patients. At 27-28 gestational weeks, umbilical cord area and Wharton's jelly values were found to be statistically different in macrosomic fetuses compared with non-macrosomic fetuses for both groups (for cord area, P = 0.012; for Wharton's jelly, P = 0.001). Additionally, umbilical cord diameter vein and artery values were not statistically different between the two groups when macrosomic fetuses were compared with non-macrosomic fetuses. At 36-37 gestational weeks, when the relationship between umbilical cord components and birth weight was examined, there was a statistically significant difference when comparing macrosomic fetuses with non-macrosomic fetuses. There was a statistically significant correlation between umbilical cord area, umbilical cord diameter and fetal weight estimation at 36-37 gestational weeks. HbA1c values and fetal macrosomia did not show a statistically significant relationship (P = 0.701). A significant relationship between umbilical cord components and birth weight was not specific for the diabetic group. There was a significant relationship between birth weight and umbilical cord components for the control group as well. If the estimated fetal weight is combined with umbilical cord components, macrosomic fetuses can be predicted with more accuracy.