An ultrasound scan sends sound waves through your womb (uterus). These waves bounce off your baby as echoes. The echoes are then turned into an image on a screen that shows your baby’s position and movements.
Hard tissues, such as bone, reflect the most sound waves and so make the biggest echoes. These appear white in the image, and soft tissues appear grey. Fluids, such as the amniotic fluid surrounding your baby, appear black. This is because the sound waves go through them with no echoes.
The person performing the scan (sonographer) will look at these different shades to interpret the images.
Your first scan can be very exciting because it gives you a first glimpse of your baby. Your sonographer may even print out the image of your baby and give it to you as a keepsake. However, you will need to ask at the start of your scan, and your hospital may charge for this service.
Some private ultrasound clinics will allow you to download an image of your scan to your phone.
Although it's great to have that first photo to keep and share, the purpose of the scan is to check how many babies you're carrying, and whether they're developing normally.
Your first scan won't be able to tell you the sex of your baby just yet.
A first-trimester scan will check that your baby's heart is beating and also look at the basic anatomy of your baby’s head, abdominal wall, and limbs.