What is the difference between 2D, 3D and 4D ultrasounds?

2D ultrasound is the traditional method used for years. They provide flatter, two-dimensional, black and white images of your baby. 3D ultrasound is an advanced method which captures a true, three-dimensional image of your baby, often allowing the ability to see specific facial features and well-defined formation. 4D ultrasound is an actual moving three-dimensional image of your baby in utero. Actions such as yawning, turning and even subtle movements can be seen. There have even been cases where expectant parents watched as their child sucked their thumb and peacefully slept!