The umbilical artery blood flow velocity waveform in relation to fetal breathing movements, fetal heart rate and fetal behavioural states in normal pregnancy at 37 to 39 weeks.
In 19 normal pregnancies between 37 and 39 weeks of gestation, the blood flow velocity waveform (FVW) of the umbilical artery was studied in relation to fetal breathing movements, fetal heart rate (FHR) and the fetal heart rate patterns (FHRPs) A and B. FHRP A is stable, with a narrow oscillation bandwidth, FHRP B shows a wider oscillation bandwidth. Although for state-assessment it is necessary to record three variables simultaneously, the linkage of these variables in the near-term healthy fetus is such, that FHRP A and B may be used for the assignment of behavioural states 1F and 2F. The FVW was characterized by the Pulsatility-Index (PI). Presence of fetal breathing movements strongly disturbed the regularity of the FVW. A significant inverse relationship between FHR and PI was established. A weighted regression coefficient was calculated: PI decreases 0.0075 with an increase of FHR of 1 beat per minute (PI140 = PI / 0.0075(FHR - 140]. The PI was higher during periods of FHRP A as compared to FHRP B. However, this difference disappeared, when the influence of FHR was taken into account by normalising all PIs to a standard heart rate level of 140 bpm. One should perform the umbilical artery blood flow measurements in absence of fetal breathing--(causing irregularity of the FVW) and body movements (because of accompanying FHR accelerations) and FHR should be taken into account when evaluating the FVWs.
D001783:Blood Flow Velocity; D005133:Eye Movements; D005260:Female; D005324:Fetal Movement; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D012119:Respiration; D014469:Umbilical Arteries / Q000502:physiology*