1. The significance of four-dimensional color ultrasound in 6 months of pregnancy. Four-dimensional color ultrasound is a very important examination method during pregnancy. Four-dimensional color ultrasound performed at 6 months of pregnancy can more clearly observe the development of the fetus, including its size, shape, movement, etc. In addition, four-dimensional color ultrasound can also detect some fetal abnormalities, such as malformations, congenital heart disease, etc.