3D - 2

What is the difference between a 3D and a 4D ultrasound?

I've seen both terms but I don't know what the difference is. Also -- My doctors office offers a free 4D that I'm getting next week. I'll be almost 29 weeks. What can I expect to see? Thanks.

Public Comments

1. 3D is the still photograph of the baby - 4D ultrasound represents the difference between video and still photograph. Through this technology, your baby's image is viewed like a live action -
2. 3d is still photos of the baby where you can see it's face and 4d is actually watching the baby move. At 29 weeks the baby should be pretty big and you'll be able to see some of the facial features and such. They will probably change done when you actually have the baby because he/she still had some growing to do. My obgyn offered them every time I got an ultrasound and at 38 weeks you could see my sons face really good and he looked exactly the same when he was born a week later!
3. my dr explained that the ultrasound itself is in 4d but when they print out the pict. that is considered 3d since not as much resolution.
4. 3D is exactly what you think - a three dimensional image as opposed to a regular 2D ultrasound. With 4D, it's just like the 3D but the 4th dimension is time, so you can actually see the baby moving in 3D.