title: Normal fetal cardiac flow velocity waveforms between 11 and 16 weeks of gestation.
abstract: OBJECTIVE
  The purpose of our study was to determine the nature of fetal cardiac flow velocity waveforms in late-first- and early-second-trimester pregnancies.
  
  
  METHODS
  Eighty-eight normal pregnancies were studied according to a cross-sectional study design between 11 and 16 weeks of gestation.
  
  
  RESULTS
  Fetal waveforms at the semilunar level showed a gestational age-related rise in peak systolic flow velocities, with significantly higher velocities in the ascending aorta. Similarly, a gestational age-related rise in peak-E wave (early diastolic filling) and peak-A wave (atrial contraction) velocity was observed at the atrioventricular level, with significantly higher velocities at the tricuspid valve level.
  
  
  CONCLUSIONS
  Compared with late gestation, these data suggest a reduced ventricular compliance or ventricular relaxation rate and a raised cardiac afterload in the normally developing late-first- and early-second-trimester fetus.
authors.affiliation: Department of Obstetrics and Gynecology, Academic Hospital, Rotterdam-Dijkzigt, The Netherlands.
authors.forename: J W
authors.initials: JW
authors.lastname: Wladimiroff
authors.forename: P A
authors.initials: PA
authors.lastname: Stewart
authors.forename: M T
authors.initials: MT
authors.lastname: Burghouwt
authors.forename: T
authors.initials: T
authors.lastname: Stijnen
mesh_terms: D000328:Adult; D001011:Aorta / Q000000981:diagnostic imaging; D001783:Blood Flow Velocity; D003430:Cross-Sectional Studies; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging / Q000502:physiology*; D005865:Gestational Age; D006351:Heart Valves / Q000000981:diagnostic imaging; D006801:Humans; D011247:Pregnancy; D011651:Pulmonary Artery / Q000000981:diagnostic imaging; D012016:Reference Values; D014463:Ultrasonography