Ultrasound scans use sound waves to build a picture of the baby in the womb.
The scans are completely painless, have no known side effects on mothers or babies, and can be carried out at any stage of pregnancy.
Most scans are carried out by specially trained staff called sonographers.
The procedure is carried out in a dimly lit room so the sonographer is able to get good images of your baby. You will then be asked to lower your skirt or trousers to your hips and raise your top to your chest.
Please ask you hospital about this before your appointment.