Study limitation
The study was limited in that it was relatively small research and did not recruit CHD fetuses. We expect to carry out a multi-center study in a normal screening population to evaluate the sensitivity and specificity of this detailed scanning procedure in cardiac screening. Besides, to our acknowledgment, the study about the R-flow on fetal echocardiography is rare. We expect the advanced application of R-flow on the prenatal diagnosis of the fetal heart.