3D and 4D ultrasounds are optional. They're not standard prenatal tests. Doctors often give them as a courtesy to women who want them. Not all doctors have access to 3D or 4D ultrasounds.

which happens between weeks 18 and 22 of your pregnancy. The typical ultrasound creates a two-dimensional cross-sectional image of your baby. Some facilities advertise 3D and even 4D ultrasounds ...