Venous liver blood flow and regulation of human fetal growth: evidence from macrosomic fetuses

OBJECTIVE: Experimental studies show that fetal liver venous perfusion is a determinant for growth in utero. Here we explore the relationship between fetal venous blood flow to the liver and macrosomia. STUDY DESIGN: From diameter and blood flow velocity measurements, we derived liver venous blood flow in a longitudinal ultrasound study of 25 macrosomic fetuses of nondiabetic mothers during the second half of pregnancy. RESULTS: Compared with appropriately growing fetuses, macrosomic fetuses directed more umbilical blood to the liver tissue, with correspondingly less contribution from the portal circulation when normalized for fetal weight. Whereas total venous liver blood flow showed no late gestation rise in the reference population, it continued to increase in macrosomic fetuses and was accompanied by greater fetal weight. CONCLUSION: The direct relationship between venous liver blood flow and macrosomia in the fetus supports the concept that intrauterine growth is linked to the amount and distributional pattern of venous liver perfusion.