Z-score reference ranges for pulsed-wave Doppler indices of the cardiac outflow tracts in normal fetuses

  • Yan Kai Mao
  • Bo Wen ZhaoEmail author
  • Li Zhou
  • Bei Wang
  • Ran Chen
  • Shan Shan Wang
Original Paper


To determine Z-score equations and reference ranges for Doppler flow velocity indices of cardiac outflow tracts in normal fetuses. A prospective cross-sectional echocardiographic study was performed in 506 normal singleton fetuses from 18 to 40 weeks. Twelve pulsed-wave Doppler (PWD) measurements were derived from fetal echocardiography. The regression analysis of the mean and the standard deviation (SD) for each parameter were performed against estimated fetal weight (EFW) and gestational age (GA), in order to construct Z-score models. The correlation between these variables and fetal heart rate were also investigated. Strong positive correlations were found between the twelve PWD indices and the independent variables. A linear-quadratic regression model was the best description of the mean and SD of most parameters, with the exception of the velocity time interval (VTI) of ascending aorta against EFW, which was best fitted by a fractional polynomial. Z-score equations and reference values for PWD indices of fetal cardiac outflow tracts were proposed against GA and EFW, which may be useful for quantitative assessment of potential hemodynamic alternations, particularly in cases of intrauterine growth retardation and structural cardiac defects.


Z-score Reference ranges Doppler flow velocity waveform Fetal echocardiography Fetal cardiac outflow tract 



This study was supported by funding from Zhejiang Province Medical Science and Technology planning projects (Grant No. 2017203109), and we thank everyone in the study group for their efforts and devotion.


This study was supported by funding from Zhejiang Province Medical Science and Technology planning projects (Grant No. 2017203109).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

Ethical approval

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards.


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Copyright information

© Springer Nature B.V. 2019

Authors and Affiliations

  1. 1.Department of Diagnostic Ultrasound & Echocardiography, Sir Run Run Shaw HospitalZhejiang University School of MedicineHangzhouPeople’s Republic of China
  2. 2.Department of Ultrasonic MedicineTongde Hospital of Zhejiang ProvinceHangzhouPeople’s Republic of China
  3. 3.Department of UltrasonographyHangzhou Xixi Hospital of Zhejiang ProvinceHangzhouPeople’s Republic of China

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