Objectives: To provide reference ranges for fetal cardiac parameters by using HeartAssist™, an automated system for measuring such parameters, in 17 large referral centres in South Korea.Methods: This prospective study included normal singleton fetuses between 16.0 and 36.6 weeks of gestational age (GA) from October 2022 to February 2023.Video clips of the fetal hearts were collected, and a total of 34 parameters were measured in six cardiac views.In the four chamber view, we measured cardiac axis; thoracic area and circumference; heart area and circumference; atrial widths and