Here the four-dimensional and five-dimensional refers to the fetal ultrasound detection, the two in the image content, popularity, price, etc. There are some differences, such as image content, four-dimensional ultrasound can observe the fetus in the uterus dynamic changes, and five-dimensional ultrasound examination of the more clear, but also can be recorded into a more detailed image, enhance the ability of the detector and so on. 1. Image content: four-dimensional ultrasound can observe the dynamic changes of the fetus in the uterus, while the five-dimensional ultrasound examination is more clear, with an additional ultrasound probe, but also can be recorded into a more detailed image, enhancing the ability to detect malformations. 2. Popularity: the current four-dimensional ultrasound is more popular, five-dimensional ultrasound due to more advanced technology, the current has not been completely popularized. 3. Price: five-dimensional ultrasound than four-dimensional more than one dimension, due to the technology to enhance the examination price is more expensive than four-dimensional ultrasound. Generally, 4D ultrasound is about 200~400 dollars, 5D ultrasound is usually more than 500 dollars. If a woman is pregnant, it is recommended that she actively undergoes Down syndrome screening and seeks timely medical attention to select the appropriate modality for her condition.