title: Human fetal cardiac function during the first trimester of pregnancy.
abstract: OBJECTIVE
  To investigate first trimester human fetal cardiac function in relation to cardiac volume blood flow, and peripheral arterial and venous blood flow patterns.
  
  
  METHODS
  Transvaginal Doppler ultrasonography was performed in 16 uncomplicated pregnancies at 6+, 7+, 8+, 9+, and 10+ gestational weeks. The shape of the inflow waveform and the presence of atrioventricular valve regurgitation (AVVR) were noted. The outflow mean velocity (Vmean) was calculated. The proportions of the isovolumetric relaxation (IRT%) and contraction times (ICT%) of the cardiac cycle were defined. Ductus venosus and umbilical artery pulsatility indices (PI) were obtained.
  
  
  RESULTS
  Every inflow waveform was monophasic before 9+ weeks. At 9+ weeks 11 of 16 and at 10+ weeks all waveforms were biphasic. At 7+ and 8+ weeks AVVR was documented in one case. At 9+ and 10+ weeks AVVR was present in four and seven fetuses, respectively. Mean (SD) outflow Vmean increased between 6+ and 8+ weeks from 3.6 (1.5) to 8.4 (3.0) cm/s (p < 0.05). IRT% decreased significantly from 6+ to 7+ weeks (39.8 (2.6) to 19.2 (6.2), p < 0.001). ICT% decreased between 8+ and 9+ weeks from 13.2 (4.0) to 8.5 (2.5) (p < 0.05). Ductus venosus PIs were unchanged. Umbilical artery Vmean increased between 7+ and 10+ weeks from 1.59 (0.51) to 5.06 (1.06) cm/s (p < 0.001) and PIs remained unchanged.
  
  
  CONCLUSIONS
  The first trimester of pregnancy is characterised by significant improvements in cardiac diastolic and systolic function with a concomitant increase in cardiac volume blood flow. At 10+ weeks AVVR is a common finding. Placental volume blood flow increases significantly with no change in the placental vascular impedance.
authors.affiliation: Department of Obstetrics and Gynaecology, University of Oulu, Oulu, Finland.
authors.forename: K
authors.initials: K
authors.lastname: Mäkikallio
authors.forename: P
authors.initials: P
authors.lastname: Jouppila
authors.forename: J
authors.initials: J
authors.lastname: Räsänen
mesh_terms: D001783:Blood Flow Velocity / Q000502:physiology; D003971:Diastole / Q000502:physiology; D005260:Female; D005318:Fetal Heart / Q000000981:diagnostic imaging / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011446:Prospective Studies; D013599:Systole / Q000502:physiology; D014262:Tricuspid Valve Insufficiency / Q000503:physiopathology; D018608:Ultrasonography, Doppler / Q000379:methods; D014469:Umbilical Arteries / Q000502:physiology