In conventional 2D scanning the ultrasound image is made up of a series of thin slices and only one slice can be seen at any one time. Although the image is very informative the picture you see does not look like a baby. With 3D ultrasound a volume of echoes is taken which can be stored digitally and shaded to produce life like pictures of the fetus. 4D just means that these life like pictures can be seen to move in real time so the activity of the baby inside your womb can be studied.

What are the advantages of 3D/4D ultrasound?

The examination time should be shorter because the baby's anatomy can be studied in any plane from the stored computer image.

Some parts of the baby's anatomy can be seen much more clearly than with 2D ultrasound, especially the face, arms, legs, fingers and toes. For example cleft palate has been shown to be more clearly seen with 3D ultrasound.

In addition, activities of the baby inside the womb can be seen which are difficult or impossible to identify on 2D scanning. For example with 4D scanning the fetus can now be seen to yawn, cry, swallow, blink and perform intricate finger movements. These activities can be seen even in mid pregnancy although they become more common as pregnancy advances.

Bonding between parents and baby has been shown to be stronger when the 3D image is seen compared to the 2D image because the picture of the baby is more realistic. Improved bonding has been shown to improve the mother's care of herself and therefore her baby.

Will I always get a beautiful picture of my baby?

Usually, but not always. Sometimes if the baby is persistently looking face down, i.e. towards your spine it may be difficult to see the baby's face. If this happens, a repeat scan in one hour will usually succeed because the baby has turned to a favourable position.

Could 3D/4D scanning be unsafe for my baby?

Despite extensive studies over 30 years ultrasound has not been shown to cause any harm to mother or baby. Indeed routine scanning of all pregnancies is now normal throughout the whole of Europe. In 3D/4D scanning exactly the same type and intensity of ultrasound is used as with conventional scanning. 3D scanning in fact should reduce the exposure time as by storing the data on a computer the baby's anatomy can be examined off line and not by continual scanning. 4D ultrasound by showing movements will be similar to a conventional scan in terms of exposure.

If I have a 3D scan do I need to have a conventional scan in my own hospital?

It is very important that you go through the hospital routine so that no antenatal test is missed out. By having a 3D scan however, you will have a professional, detailed scan of the baby's growth and anatomy and this information will be sent to your general practitioner.

When is the best time to have a 3D/4D scan?

Good pictures of your baby can be obtained throughout your pregnancy. In early pregnancy you will see the whole baby moving its arms and legs but details of the face are indistinct. Later in pregnancy you will see clear images of your baby's features