For expectant mothers, every prenatal ultrasound examination is very expected. At the same time, there are many puzzles: should we do three-dimensional or four-dimensional color Doppler ultrasound in the second trimester of pregnancy when we encounter “large row malformation” (i.e. systematic prenatal screening of the fetus)? What is the difference between two-dimensional, three-dimensional and four-dimensional color Doppler ultrasound? Listen to Lin Qizhi, chief physician of Obstetrics and G...