Abstract
BackgroundPregestational diabetes is associated with fetal macrosomia, and umbilical perfusion of the fetal liver has a role in regulating fetal growth. We therefore hypothesized that pregestational diabetes alters fetal liver blood flow depending on degree of glycemic control.MethodsIn a prospective study, 49 women with pregestational diabetes underwent monthly ultrasound examinations during 24–36 gestational weeks. Blood flow was determined in the umbilical vein, ductus venosus and portal vein, and blood velocity was measured in the left portal vein, the latter reflecting the watershed between splanchnic and umbilical flow. The measurements were compared with reference values by z-score statistics, and the effect of HbA1c assessed.ResultsThe umbilical venous flow to the liver (z-score 0.36, p = 0.002), total venous liver flow (z-score 0.51, p<0.001) and left portal vein blood velocity (z-score 0.64, p<0.001), were higher in the study group. Normalized portal venous flow was lower (z-score -0.42, p = 0.002), and normalized total venous liver flow tended to be lower after 30 gestational weeks (z-score -0.54, p = 0.047) in the diabetic pregnancies compared with reference values from a low-risk population. The left portal vein blood velocity was positively, and the portal fraction of total venous liver flow negatively correlated with first trimester HbA1C.ConclusionsIn spite of increased umbilical blood distribution to the fetal liver, graded according to glycemic control, the total venous liver flow did not match third trimester fetal growth in pregnancies with pregestational diabetes, thus contributing towards increased perinatal risks and possibly altered liver function with long-term metabolic consequences.
Highlights
Blood flow was determined in the umbilical vein, ductus venosus and portal vein, and blood velocity was measured in the left portal vein, the latter reflecting the watershed between splanchnic and umbilical flow
Normalized portal venous flow was lower (z-score -0.42, p = 0.002), and normalized total venous liver flow tended to be lower after 30 gestational weeks (z-score -0.54, p = 0.047) in the diabetic pregnancies compared with reference values from a low-risk population
The left portal vein blood velocity was positively, and the portal fraction of total venous liver flow negatively correlated with first trimester HbA1C
Summary
Pregnancies complicated by pregestational diabetes mellitus (PGDM) are associated with increased perinatal morbidity and mortality [1], and fetal macrosomia is related to these adverse neonatal outcomes [2]. The distribution of the nutrient rich umbilical venous blood to the liver has been suggested to be a mechanism for regulation of fetal growth [9]. This is based on experimental studies showing that increasing liver flow from the umbilical vein leads to higher cell proliferation in the liver, heart, skeletal muscle and kidneys in fetal lamb [9]. Studies of human low-risk pregnancies have shown that larger fetal size is associated with higher umbilical venous liver flow as a response to maternal glucose intake [10]. Pregestational diabetes is associated with fetal macrosomia, and umbilical perfusion of the fetal liver has a role in regulating fetal growth. We hypothesized that pregestational diabetes alters fetal liver blood flow depending on degree of glycemic control
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