Prospective study on sonographic measurement of umbilical cord thickness, foetal fat layer, interventricular septal thickness as predictors of macrosomia in fetus of women with gestational diabetes mellitus

Abstract

Introduction: Fetal macrosomia, defined as birth weight exceeding 4000 grams, is associated with increased perinatal morbidity and mortality, particularly in pregnancies complicated by gestational diabetes mellitus (GDM). Conventional methods of estimating fetal weight often lack accuracy in predicting macrosomia in diabetic pregnancies, where abnormal fat distribution patterns may confound standard biometric measurements. This prospective study aimed to evaluate the efficacy of three sonographic parameters—umbilical cord thickness, fetal fat layer thickness, and interventricular septal thickness—as predictors of fetal macrosomia in women with GDM. Methods: A total of 123 pregnant women with GDM between 34-40 weeks of gestation were enrolled in this prospective study. Comprehensive maternal data including age, BMI, and glycemic parameters were recorded. Sonographic measurements of umbilical cord thickness, fetal fat layer, and interventricular septal thickness were performed, and their association with actual birth weight and delivery outcomes was analyzed. Results: Out of 123 pregnancies, 77 (62.6%) resulted in macrosomic babies. Significant associations were found between macrosomia and maternal BMI (p<0.001), HbA1c levels (p<0.001), umbilical cord thickness ≥25 mm (p<0.001), fetal fat layer ≥4.5 mm (p<0.001), and interventricular septal thickness ≥3.9 mm (p<0.001). Umbilical cord thickness demonstrated the strongest correlation with birth weight (r=0.792, p<0.001) and showed excellent diagnostic accuracy with sensitivity of 93.3% and specificity of 85.4%. Fetal fat layer thickness exhibited high specificity (93.3%) and positive predictive value (97.3%), while interventricular septal thickness showed good specificity (85%) but lower sensitivity (71.8%). Conclusion: Sonographic measurements of umbilical cord thickness, fetal fat layer, and interventricular septal thickness are valuable predictors of fetal macrosomia in GDM pregnancies. Integration of these parameters with maternal factors may enhance the accuracy of macrosomia prediction, potentially improving clinical decision-making and optimizing maternal and neonatal outcomes.