Conventional ultrasound, usually offered to mums at 12 and 20 weeks, produces only two-dimensional images of the growing foetus, which have been more than enough to reassure nervous parents that baby is safe and well.

Now, new advances in ultrasound can give parents moving, real-time images of baby that can be recorded onto a CD or DVD.

So, for the first time, parents can watch and wonder at their baby's physical and behavioural characteristics while their little darling is still in the womb.

To create 3-D images, an ultrasound system determines the volume of a subject - for example, a baby - and reconstructs the image in three dimensions. But a new ultrasound machine gathers the 3-D volumes and instantly turns them into moving images. The result is live action images of an unborn child.

These developments allow parents to see detailed pictures of their unborn baby yawning rubbing their eyes and kicking.

Using this technology, images have shown that at 12 weeks unborn babies can stretch, kick and leap around the womb before the mother can feel this movement.

From 18 weeks, unborn babies can pen their eyes, even though doctors previously thought that eyelids were fused until 26 weeks.

At 26 weeks, babies display a whole range of behaviour and moods, including scratching, smiling, crying, hiccupping and sucking.

Pregnancy is nine months of hope, joy, expectation and anxiety, with the slightest tummy movement sending parents into a whirlwind of uncertainty and excitement. But new technology allows parents to witness the miracle of their unborn child's development and takes away some of the mystery of what's happening inside the bump. Riazat Butt reports on 4-D scanning

The 4-D scans, which were pioneered in London, are now available in the North west. Consultant radiologist Dr David Nicholson, who works at the private Baby Premier clinic in Altrincham, says: "Such 4-D scans are emotionally reassuring for parents. It's a thrilling and unique experience to be able to bond with your child in this way.

"For 4-D scanning we recommend a visit between 22-32 weeks, which is the best time for capturing facial images."

The most important factor when determining the quality of the images is the position of the baby. Other factors include the amount of amniotic fluid - the more the better - and the amount of tissue between the probe and the baby.

Dr Nicholson adds: "This scan shows the skin surface and external characteristics and, from a mother's point of view, it can be a fantastic experience.

"Pregnancy is quite a long haul and sometimes, when you feel the baby move and you see a 2-D image, you can't put the two together.

"Most people are fairly exhilarated when they see the 4-D image. But it's not designed to replace the conventional 2-D scan, called the anomaly scan, which checks internal organs, the spine, placenta, umbilical cord, hands and feet. This scan is taken at 20 weeks and is very important for all expectant mothers.

"The 4-D scan (which costs £195) is an additional service for parents who want to know what their baby looks like."

Ultrasound does have its limitations, as it cannot identify bone and air, so regions such as the lungs, stomach, bowel and bones are better examined using different methods that may require the use of radiation. Also the 4-D scan is not performed as a check for foetal abnormalities.

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Journalist Lizzie Gething is 33 weeks pregnant with her first child and jumped at the chance to try out this new ultrasound technology. She says: "Some friends said it would ruin the surprise, but considering we have already found out the sex and chosen a name, it seemed a bit late to start worrying abut surprises.

"In fact, the scan actually showed 'real-time' life-like images f the baby I've been carrying for almost eight months.

"At first the baby was camera-shy, with her arm across her forehead. Then she yawned, a tiny action, but one I will never forget. Along with a feeling an immense rush of love for my unborn baby, I also felt privileged that I was able to see her, so innocent and safe in the womb.

During the rest of the scan we saw her sucking her thumb and wiggling about. Sometimes her facial features were slightly difficult to make out, but as each image is shown in a strange brown sepia colour she still looked angelic in every one.

"More than just spurring me on through the final weeks of pregnancy, the scan helped me to bond with my baby. And it reassured me that everything is fine in there.

"There are moments when you worry, when perhaps you haven't felt her move for a while and your mind begins to work overtime. But this opportunity to look in on her and see all her natural movements and reactions was priceless."