Ultrasound-based prediction of fetal hyperinsulinemia: development of a fetal metabolic score.

OBJECTIVES: Gestational diabetes mellitus (GDM) is associated with fetal hyperinsulinemia, excessive adiposity, and adverse perinatal outcomes; sonographic markers of fetal adiposity, liver enlargement, and septal thickening may allow direct assessment of fetal metabolic adaptation. This study aimed to develop an ultrasound-based fetal metabolic score (FMS) estimating the risk of fetal hyperinsulinemia. METHODS: The FMS was developed from a prospective cohort of 223 pregnant women (128 with GDM, 95 controls). Sonographic markers of neonatal hyperinsulinemia were identified using umbilical cord C-peptide above the 75th percentile as the reference outcome: thigh soft tissue thickness, abdominal subcutaneous fat thickness, fetal liver length, and interventricular septal thickness. Odds ratios from logistic regression were converted into weighted integer coefficients, and continuous measurements were categorized by gestational age-adjusted percentiles into a composite score. RESULTS: Fetuses of GDM mothers showed significantly greater abdominal adiposity, liver length, and interventricular septal thickness than controls. Thigh soft tissue thickness (OR 1.62; 95 % CI 1.25-2.09; p<0.001), abdominal subcutaneous fat thickness (OR 1.57; 95 % CI 1.23-1.99; p<0.001), fetal liver length (OR 1.06; 95 % CI 1.02-1.11; p=0.004), and interventricular septal thickness (OR 1.35; 95 % CI 1.01-1.82; p=0.040) independently predicted elevated cord blood C-peptide. The FMS ranged from 0 to 44 points, integrating weighted contributions from adiposity, visceral growth, and cardiac remodeling markers. CONCLUSIONS: The FMS is a novel ultrasound-based approach for estimating fetal hyperinsulinemia risk. By integrating multiple manifestations of the fetal metabolic response to maternal hyperglycemia, it may assess fetal metabolic health more comprehensively than conventional biometry alone.