Doctors have succeeded in producing accurate three-dimensional images of babies in the womb.

Ultrasound scans were compiled on a computer to construct the model, which allows doctors to measure the size and relation of body parts as they grow.

The team started with 2D images from traditional ultrasound scans ...

The work was carried out by a research team from Trondheim University Hospital in Norway. Their results are published in The Lancet medical journal.

This means doctors would have a much clearer idea of what is going on in the womb during pregnancy.

... by compiling the images they produced contours ...

Dr Harm-Gerd Blaas led the investigation. He said the system would "make possible study of abnormal development of the embryo or early foetus and elucidate its position".

The technique offers extremely accurate images and produced 3D imaging of objects less than 10mm long.

Doctors currently have to make do with low-resolution ultrasound images.

... to produce a 3D model

The researchers said they had better results with the new technique.

They said: "The quality of the images allowed description of the outer contours and the development of organ systems."

The team precisely monitored the development of 34 embryos between seven and 10 weeks.

They said they were able to obtain the first ever accurate measurements of some parts of the head of a foetus using the technique.

History of research

Dr Wilhelm His was the inspiration for the study, the researchers said.

He made 3D reconstructions of embryos in the 19th century.

Where he used freehand drawings from laboratory samples, the Trondheim research started with ultrasound scans obtained by using a vaginal probe.

And while Dr His used wax plates of his drawings to create a model, today's researchers loaded their scans into a computer, which generated the 3D image.

The computer-generated versions are largely similar to previous attempts to produce 3D representations of a foetus.

But researchers said the much greater accuracy of their technique's measurements would reduce the misinterpretation of scans that sometime occur in embryology.