3D scans show still pictures of your baby in three dimensions. 4D scans show moving 3D images of your baby, with time being the fourth dimension. It's natural to be really excited by the prospect of your first scan. But some mums find the standard 2D scans disappointing when all they see is a grey, blurry outline. This is because the scan sees right through your baby, so the photos show her internal organs.
With 3D and 4D scans, you see your baby's skin rather than her insides. You may see the shape of your baby's mouth and nose, or be able to spot her yawning or sticking her tongue out.
An anomaly scan, also known as a mid-pregnancy scan, takes a close look at your baby and your womb (uterus). The person carrying out the scan (sonographer) will check that your baby is developing normally, and look at where the placenta is lying. Although the anomaly scan is often called a 20-week scan, you may have it any time between 18 weeks and 20 weeks plus six days.
This image shows a baby's face and hands at 20 weeks, and gives you an idea of what you will be able to see at this scan. Seeing your baby on a screen can be really exciting. You can also take your partner, friend or family member along to share the experience with you.
The main purpose of the scan is to check that your baby is developing normally, rather than whether you're expecting a boy or girl.
If you haven't already had a scan in your pregnancy, the sonographer will check that there is only one baby, and confirm your due date. The sonographer will point out your baby's heartbeat and parts of his body, such as his face and hands, before looking at him in detail. It may be hard for you to make out your baby's organs, as the sonographer will look at them as a cross section.
Your baby's bones will appear white on the scan, and his soft tissue will look grey and speckled. The amniotic fluid surrounding your baby will look black.
Your baby's face, to check for a cleft lip. Cleft palates inside a baby's mouth are hard to see and are not often picked up.
Your baby's spine, both along its length, and in cross section, to make sure that all the bones align, and that the skin covers the spine at the back.
Your baby's abdominal wall, to make sure it covers all the internal organs at the front.
Your baby's heart. The top two chambers (atria) and the bottom two chambers (ventricles) should be equal in size.
Your sonographer will also examine the major veins and arteries which carry blood to and from your baby’s heart.
Your baby's stomach. Your baby swallows some of the amniotic fluid that he lies in, which is seen in his stomach as a black bubble.
Your baby's arms, legs, hands and feet. The sonographer will look at your baby's fingers and toes.
The placenta, umbilical cord and the amniotic fluid.