Vinayagam D, et al. - Reference ranges of maternal central hemodynamic parameters during pregnancy were constructed in this work. Secondly, researchers searched for the maternal and pregnancy characteristics that influence these hemodynamic parameters. Maternal age, height, and weight were found significantly influencing maternal hemodynamics. USCOM-1A-specific reference ranges and a calculator for stroke volume, cardiac output and systemic vascular resistance in uncomplicated pregnancies that correct for maternal age, height and weight were provided. This should enable clinical application and comparison in both uncomplicated and pathological pregnancies.