The pictures tell the story. Baby's first feed, first smile, first steps, first birthday, first everything. The record is there to be scrutinised and treasured. But why wait until birth? Why not start this pictorial history in utero?

Ultrasound imaging may have entered obstetrics as a medical tool, but it is now establishing itself as something much more. Go to the web and you can find scores of companies willing to exploit the powerful emotional impact of seeing your fetus by generating still pictures to grace the first page of the album or moving ones to play on the home computer. Not medically necessary, of course. An indulgence, certainly, but harmless. Or is it?

Not everyone takes a benign view of non-medical ultrasonography. The US Food and Drugs Administration, the American Institute of Ultrasound in Medicine, and the French Academy of Medicine are among several official bodies that have reservations about such use of the technology. In the United Kingdom, Dr Paul Sidhu, chairman of the scientific and education committee of the British Medical Ultrasound Society, detects what he describes as an “overall sense of disapproval” among his colleagues for this development.

What was once the casual offer of hazy black and white Polaroid images during a routine antenatal scan has become a slick business transaction. Driving this transformation has been the big improvement in ultrasound technology. The early two dimensional black and white scans gave a succession of poor resolution slices through the womb and its contents. Better technology sharpened the images. Then machines arrived that could assemble the slices into a 3D picture of the whole fetus with …