Fetal pulmonary venous blood flow velocities in a normal population and new calculated reference values.

Objective: The aim of this study is to establish new Doppler reference values in a population with normal pulmonary veins during different phases of the fetal cardiac cycle for maximum blood flow velocities during ventricular systole (S), early ventricular diastole (D), atrial contraction (a), intensity-weighted mean velocity (Vmean) and the indices derived from these parameters [(S - a)/D] and [(S - a)/Vmean].

Methods: The pulsed-wave color advanced dynamic flow Doppler technique was used in a prospective cross-sectional study of 365 low-risk pregnancies between 18 and 41 completed gestational weeks. Reference ranges were calculated for the individual measuring parameters based on a growth function from a four-parameter class of monotonic continuous functions according to the smallest square principle.

Hematological changes in severe early onset growth-restricted fetuses with absent and reversed end-diastolic flow in the umbilical artery.

Background: Erythropoietin seems to play an important role in the regulation of fetal hypoxemia. The present prospective study was designed to determine if changes in erythropoietin levels can be found in fetuses with severe early-onset growth restriction and hemodynamic compromise.

Methods And Results: Erythropoietin, hemoglobin, hematocrit, platelet counts, normoblasts, lacate, arterial and venous blood gasses in the umbilical cord were determined in 42 fetuses with fetal growth restriction (IUGR) with absent (zero-flow) and 26 IUGR fetuses with retrograde end-diastolic flow (reverse-flow) in the umbilical artery.