I spoke to my doctor about getting the 3D/4D ultrasound but he said he didn't recommend them. He told me to go on the OB website and see what other doctors say about it. He told me that it has no medical benefit and all it can do is show you what your baby will look like. He said they don't know the effects it could have on the baby being it is stronger than a regular US.
Others I have spoken to that have gotten said it had no effect but being I had a miscarriage before I didn't want to do anything that could jeopardize my baby.
My doctors office offers the 3d ultrasound. On one of my early ultrasounds(like 7 weeks) she printed us a picture in the 3d just so it looked more like something then just a bloob. Um other wise my office offers a package for around $150 later in your preg to do a whole like 45 min session and get a dvd and tons of pictures and stuff. I guess it all depends on where your at, a friend ofmine that lives in PA said there were centers you could go to to do the 3d but it was very expensive.