The role of umbilical-portal venous hemodynamics in fetal macrosomia pathogenesis in pregnancy complicated by diabetes mellitus

BACKGROUND: During pregnancy complicated by diabetes mellitus, the risks of developing fetal macrosomia and other perinatal complications increase. Redistribution of blood flow in the fetal umbilical-portal venous system may be an important but poorly understood compensatory mechanism that affects macrosomic fetal growth. AIM: The aim of this study was to determine the features of the fetal umbilical-portal venous hemodynamics in pregnant women with various types of diabetes mellitus and the absence of carbohydrate metabolism disorders, taking into account the gestational age and the macrosomic fetal growth. MATERIALS AND METHODS: In this prospective cohort study, 86 pregnant women with pregestational diabetes mellitus, 44 pregnant women with gestational diabetes mellitus and 58 patients without carbohydrate metabolism disorders underwent ultrasound examinations from 30+0 to 41+3 weeks of gestation. During ultrasound, we performed Doppler assessment of venous hemodynamic parameters in the vessels of the umbilical-portal venous system, with volumetric blood flow calculated for each vessel. Additionally, the total liver volumetric blood flow and ductus venosus shunt fraction were calculated. RESULTS: The presence of fetal macrosomia in patients from the pregestational diabetes mellitus group is associated with an increase in the volumetric blood flow of the umbilical vein by 89.5 ml/min (p = 0.003) and the left portal vein by 33.3 ml/min (p = 0.008), as well as the total volumetric blood flow of the fetal liver by 95.7 ml/min (p = 0.001) compared with normal-weight fetuses. At the same time, the ductus venosus shunt fraction decreased in macrosomic fetuses by 3.83% (p = 0.001). In the gestational diabetes mellitus and control groups, despite the tendency for these parameters to increase in fetuses with macrosomia, the differences did not reach statistical significance. With a left portal vein volume flow threshold of 94.51 ml/min, the sensitivity and specificity for predicting large births were 84.46 and 72.09%, respectively. CONCLUSIONS: Pregestational diabetes mellitus in the mother is associated with a priority redistribution of blood flow to the fetal liver and is accompanied by a decrease in the ductus venosus shunt fraction. The severity of these hemodynamic changes increases in the presence of fetal macrosomia, which confirms the role of liver perfusion in the regulation of fetal growth in uncomplicated pregnancy and maternal diabetes mellitus.