title: Assessment of fetal heart rate variability and velocity variability by Doppler velocimetry of the descending aorta at 10-20 weeks of gestation.
abstract: OBJECTIVE
  Determination of gestational age-related modulations in fetal heart rate and descending aorta blood flow velocity in the early human fetus and comparison of aortic variability data with data obtained from the umbilical artery. It is hypothesized that these modulations present in the umbilical artery also occur in the descending aorta.
  
  
  METHODS
  Doppler studies of descending aorta velocity waveforms were performed at 10-20 weeks in 55 normal pregnant women. In 24 of the 55 women, Doppler recordings from both the descending aorta and the umbilical artery were collected. Absolute values and variability of fetal heart rate, peak systolic and time-averaged velocities were determined from flow velocity waveforms of at least 18 s in duration.
  
  
  RESULTS
  From 10 to 20 weeks of gestation, the descending aorta peak systolic and time-averaged velocities increased, whereas the fetal heart rate decreased. The descending aorta peak systolic variability also increased. However, the time-averaged velocity variability and fetal heart rate variability remained constant during the study period. In the subset of 24 women, the fetal heart rate variability and velocity variability data from the descending aorta and umbilical artery were not significantly different.
  
  
  CONCLUSIONS
  Reproducible fetal heart rate and velocity variability data can be derived from the descending aorta and umbilical artery. The increase in heart rate variability observed in the umbilical artery was not seen in recordings obtained from the descending aorta. Different fetal activity states may be the underlying mechanism for these heart rate variability discrepancies.
authors.affiliation: Department of Obstetrics and Gynecology, Academic Hospital Rotterdam-Dijkzigt, The Netherlands.
authors.forename: N T
authors.initials: NT
authors.lastname: Ursem
authors.forename: E B
authors.initials: EB
authors.lastname: Clark
authors.forename: B B
authors.initials: BB
authors.lastname: Keller
authors.forename: W C
authors.initials: WC
authors.lastname: Hop
authors.forename: J W
authors.initials: JW
authors.lastname: Wladimiroff
mesh_terms: D001013:Aorta, Thoracic / Q000000981:diagnostic imaging*; D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D005260:Female; D005323:Fetal Monitoring / Q000379:methods*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D015203:Reproducibility of Results; D013599:Systole; D018608:Ultrasonography, Doppler / Q000379:methods*; D016216:Ultrasonography, Prenatal / Q000379:methods*; D014469:Umbilical Arteries / Q000000981:diagnostic imaging