title: Fetal cardiac output and its distribution to the placenta at 11-20 weeks of gestation.
abstract: OBJECTIVE
  To measure serial changes in cardiac output (CO) and its fraction distributed to the placenta at 11-20 weeks of gestation.
  
  
  METHODS
  Blood flow velocities, and diameters of the aorta, pulmonary artery and umbilical vein, were measured longitudinally in 143 fetuses using pulsed-wave Doppler and two-dimensional ultrasound examination.
  
  
  RESULTS
  Volume blood flow of the aorta (left ventricular CO) and the pulmonary artery (right ventricular CO) increased in a similar manner with advancing gestational age. The combined cardiac output (CCO) increased from 9 mL/min to 121 mL/min, and the placental volume blood flow (Q(uv)) increased from 1.2 mL/min to 25.3 mL/min during 11-20 weeks of gestation. The fraction of CCO diverted to the placenta increased from 14% at 11 weeks to 21% at 20 weeks.
  
  
  CONCLUSIONS
  We have established longitudinal reference ranges for fetal CO and Q(uv) at 11-20 weeks of gestation. The fraction of CCO distributed to the placenta increased significantly during this period, reflecting rapid placental growth and establishment of a low-resistance circulation.
authors.affiliation: Central Maternity Unit, City of Tampere, Tampere, Finland.
authors.forename: T
authors.initials: T
authors.lastname: Vimpeli
authors.forename: H
authors.initials: H
authors.lastname: Huhtala
authors.forename: T
authors.initials: T
authors.lastname: Wilsgaard
authors.forename: G
authors.initials: G
authors.lastname: Acharya
mesh_terms: D000293:Adolescent; D000328:Adult; D000465:Algorithms; D001011:Aorta / Q000502:physiology; D001783:Blood Flow Velocity / Q000502:physiology; D002302:Cardiac Output / Q000502:physiology*; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging / Q000502:physiology*; D005865:Gestational Age; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006801:Humans; D008297:Male; D010920:Placenta / Q000098:blood supply* / Q000000981:diagnostic imaging; D011247:Pregnancy; D011446:Prospective Studies; D011651:Pulmonary Artery / Q000502:physiology; D015203:Reproducibility of Results; D016216:Ultrasonography, Prenatal / Q000379:methods; D014471:Umbilical Veins / Q000502:physiology; D055815:Young Adult