[Doppler studies of arterial uterofetoplacental blood flow before and during labor].

The encouraging results obtained using pulsed Doppler sonography for antepartal diagnosis gave cause to use the method during labor. For this purpose a group with normal course of pregnancy was examined by Doppler sonography. This group was compared with a similar group examined by the same method at onset of labor with the cervix beginning to dilate, or with premature rupture. A comparison of the usual Doppler parameters, uterine arteries, umbilical artery and fetal aorta, recorded in contraction-free phases, showed no differences between the two groups. A third group was examined by Doppler sonography during labor with average or late cervix dilatation. In this case the Doppler parameters for the contraction phases were compared with those for the contraction-free phases. With adequate utero-placental supply during labor, the changes in the Doppler parameters for the uterine arteries due to contraction indicate a reduction in blood flow. The blood flow in the umbilical artery remains unaffected during normal labor. In the fetal aorta the blood flow velocity drops significantly due to contractions, while the peripheral resistance is unchanged. The elimination of the end-diastolic shift in frequency in the fetal aorta during labor indicates a fetal supply deficiency, as shown by Doppler measurements during birth in cases with pathologic cardiotokograms.