title: Intracerebral, aortic, and umbilical artery flow velocity waveforms in the late-first-trimester fetus.
abstract: OBJECTIVE
  Our objectives were to determine the success rate in obtaining flow velocity waveforms in the first-trimester fetal circulation and to establish possible preferential flow to the fetal cerebrum at this early stage of gestation.
  
  
  METHODS
  Flow velocity waveform recordings were made in the umbilical artery, fetal descending aorta, and fetal intracerebral arteries in 30 normal pregnancies between 11 and 13 weeks of gestation.
  
  
  RESULTS
  Technically acceptable waveforms were obtained from the descending aorta in 15 fetuses, from the intracerebral circulation in 17 fetuses, and from the umbilical artery in all 30 fetuses. Absent end-diastolic velocities in the descending aorta and umbilical artery were associated with forward flow throughout the cardia cycle in intracerebral arteries.
  
  
  CONCLUSIONS
  A relatively low cerebral vascular resistance in the late-first-trimester normal fetus is suggested.
authors.affiliation: Academic Hospital Rotterdam-Dijkzigt, Erasmus University Rotterdam, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Wladimiroff
authors.forename: T W
authors.initials: TW
authors.lastname: Huisman
authors.forename: P A
authors.initials: PA
authors.lastname: Stewart
mesh_terms: D000328:Adult; D001011:Aorta / Q000196:embryology* / Q000502:physiology; D001783:Blood Flow Velocity; D002536:Cerebral Arteries / Q000196:embryology* / Q000502:physiology; D005260:Female; D005333:Fetus / Q000502:physiology*; D005865:Gestational Age; D006340:Heart Rate, Fetal; D006801:Humans; D011247:Pregnancy; D014469:Umbilical Arteries / Q000502:physiology*