Z Score Reference Ranges of Fetal Cardiac Output From 12 to 40 Weeks of Pregnancy

Abstract

Objectives: To develop the Z score reference ranges of fetal cardiac output (CO) in healthy fetuses from 12 to 40 weeks of pregnancy.

Methods: A cross-sectional descriptive study was undertaken among low-risk singleton pregnancies with healthy fetuses between 12 and 40 weeks. The right ventricular cardiac output (RCO), left ventricular cardiac output (LCO), and combined cardiac output (CCO) were measured by 2-dimensional ultrasound with the Doppler velocity of the aorta and pulmonary arteries. The pregnancies were followed until delivery RESULTS: The RCO, LCO, and CCO were determined in 700 fetuses. The predictive models of the CO as a function of gestational age (GA) and biparietal diameter were identified, and the Z score reference ranges were constructed. The means and standard deviations of CO on both sides were increased with GA and biparietal diameter as power models. Nomograms for the LCO, RCO, and CCO were established (ie, RCO = 0.000148 × GA^4.283034 ; SD = 0.000131 × GA^4.026209 ; LCO = 0.000514 × GA^3.790944 ; SD = 0.000169 × GA^3.815546 ). The RCO was much more increased than the LCO with advancing GA.

Conclusions: The Z score reference ranges and percentile charts of fetal CO were constructed throughout gestation with a large sample size. This may be helpful in detection of cardiac disorders, especially cardiomyopathy, cardiac anomalies, fetal anemia, and fetal growth restriction.

Keywords: Doppler velocity; cardiac output; fetus; reference ranges; ultrasound.