Abstract

BACKGROUND
In pregnancies complicated by diabetes, fetal hyperinsulinemia increases the deposition of fat, protein and glycogen in insulin-sensitive tissues leading to macrosomia, characterized by shoulder and truncal obesity. This may result in a shoulder dystocia, birth injury or fetal asphyxia. Thus, antenatal prediction of a large fetus for gestational age (LGA) can provide important information for the prevention of obstetric and perinatal complications. However, the measurement of materrml blood glucose concentration has yielded a low sensitivity for the prediction of LGA infants. This study was performed to determine whether fetal ultrasound examination could establish the onset of accelerated fetal growth in women with gestational diabetes mellitus (GDM) and to find the ultrasound indices for prediction of LGA infant. METHODS: The study subjects consisted of 77 women with GDM who had a singleton, and 156 women with a negative screen for GDM matched for age, height, and weight. All subjects had an early ultrasound examination before 14 weeks, assuring accurate dating and did not have any other medical condition that might affect fetal growth. Two ultrasound measurements including biparietal diameter (BPD), abdominal circumference (AC) and femur length (FL) were performed at the 2nd trimester (24.7+2.7 vs. 24.1+2.4 wks, p>0.05) and the 3rd trimester (35.0+1.9 vs. 35.3+1.3 wks,p>0.05, respectively). RESULTS: Although gestational age at delivery of GDM group was earlier than the control group (39.0 +1.4 vs. 39.7+1.1, p<0.01), birth weight and frequency of LGA infant were similar between two groups (3204+439 vs. 3288+371 g, p>0.05; 27.3% vs. 20.5%, p>0.05, respectively). However, the LGA subgroup of GDM had a larger AC and longer FL at the 3rd trimester compared to the appropriate gestational age (AGA) subgroup and control group. The AC of LGA subgroup of GDM appeared to be accelerated at 33 weeks gestation compared to the control group. When the upper limit of 95% confidential interval of AC of the control group was used for a cutoff value for predicting LGA in GDM at the 3rd trimester, sensitivity and specificity was 71% and 78%, respectively. CONCLUSION: The prediction of LGA infant in women with GDM might be achieved by an ultrasound examination of fetal AC at the 3rd trimester, especially after 33 weeks gestation.

• Keywords: Key Words;Gestational diabetes;Large for gestational age infant;Ultrasound;