[Value of vascular resistance in fetal circulation during normal pregnancy]

The aim of the study is to estimate the values of resistance index (RI) in the arteries of the fetus using color doppler ultrasound. Measurements have been made in aorta, umbilical and medial cerebral artery of the fetus and in arcuate artery of the pregnant women. 50 women have been examined every 4 weeks and another 50 every 6 weeks during normal pregnancy. Resistance index has been calculated based on analyses of flow waves configuration in all of the mentioned arteries. Likeness between curves obtained in women examined every 4 and 6 weeks in obvious. The examination of mean RI values shows that vascular resistance in descending aorta remains constant during the vascular resistance in descending aorta remains constant during the all the period. In arcuate artery vascular resistance falls down until 22 week of pregnancy and then settles on constant level. RI of umbilical artery decreases during pregnancy and in median cerebral artery reaches its peak in 32/34 week of pregnancy.