Abstract

BACKGROUND
Recently we reported that the large for gestational age (LGA) fetus of women with gestational diabetes mellitus (GDM) had disproportionate growth characterized by larger abdominal circumference (AC) but similar biparietal diameter (BPD) at third trimester compared to the fetus of normal pregnant women. The AC of LGA fetus appeared to be accelerated after 33 weeks gestation, and measurement of AC could be an effective method for prediction of LGA. Thus this study was performed to find the relationship between fetal hyperinsulinemia and disproportionate growth and to find the highly sensitive index for prediction of LGA infant in GDM. METHODS: We prospectively studied ultrasono- graphic growth patterns at 30, 34, 38 gestational weeks in 20 women with GDM and 15 normal pregnant women. The ultrasonographic measurements of fetus included biparietal diameter (BPD), head circumference (HC), abdominal circumference (AC), femur length (FL), mid-thigh circumference (MTC), mid-upper arm circumference (MUAC), mid-thigh subcutaneous fat thickness (MTFT), mid-upper arm subcutaneous fat thickness (MUAFT), fetal liver length (FLL), chest circumference (CC) and heart circumference (HTC). RESULTS: Compared to the fetus of normal pregnant women and appropriate for gestational age (AGA) fetus of GDM, LGA fetus of GDM had thicker MUAFT (3.9+0.9, 5.0+1.1, 5.6+1.7 mm, p=0.008) at 34 weeks, MUAFT (5.3+0.8, 5.6+0.9, 7.2+1.4 mm p=0.045) at 38 weeks and MTFT (5.2 +1.1, 5.5+0.8, 7.1+1.5 mm, p=0.019) at 38 weeks. They also had longer MUAC (120.3+9.9, 119.4+ 8.3, 138.7+11.2 mm, p=0.020) and CC(322.6+11.7, 324.4+15.7, 351.7+15.0mm, p=.025, respectively). There was a positive correlation between umbilical venous C-peptide concentration and birthweight (r=0.626, p=0.005) and symmetry index (r=0.523, p=0.03) of newborns. There was also a positive correlation between C-peptide concentration and MUAC (r=0.449, p=0.038) and MUAFT (r=0.426, p=0.045) in GDM group. CONCLUSION: The LGA fetus of women with GDM showed an accelerated growth of predominantly subcutaneous fat tissues that should be caused by the fetal hyperinsulinemia. Ultrasonographic measurement of subcutaneous tissues may be the most sensitive index for prediction of growth abnormalities in GDM at late gestation.

• Keywords: Key Words;Gestational diabetes;Disproportionate growth;Ultrasound;