Technological advances have enabled parents to get amazing high definition ultrasound images of their unborn baby and even CD-ROMs and DVDs that can cost up to 250 pounds ($490) at commercial companies.

But experts said although there is no evidence that ultrasound can harm the developing fetus it should be used prudently.

"You should make sure the people carrying out the scans are properly trained to do it and that they have procedures in place to deal with any incidental findings," said Dr. Kevin Martin, the president of the British Medical Ultrasound Society (BMUS).

Martin said the scans were intended for medical purposes and not to provide keepsake images for parents.

"The society feels that ultrasound was developed and is intended for medical diagnosis and any such scans should be endorsed by a medical practitioner," Martin added in an interview.

Doctors often give expectant parents a photograph of their unborn child taken during a routine ultrasound scan but many commercial companies are offering parents cutting edge images and moving pictures.

A report in the British Medical journal on Friday said parent's desire for early snapshots in the womb have led to a rise in commercial companies offering what it describes as "boutique ultrasonography."

French and American experts share the concerns of BMUS.

"In the US, the FDA has long been opposed to non-medical ultrasonography," according to the journal.

Martin said the BMUS has a set of safety guidelines for the safe use of ultrasound equipment and the use of ultrasound in the first 12 weeks of pregnancy when the baby is more at risk of things going wrong.

"The society states that in the first trimester scans should not be carried out for the sole purpose of producing souvenir videos or photographs," said Martin.

"If people must have these things later in pregnancy, when there is a bit less risk to the baby, then the guidelines recommend that the output level of the machine is turned down to a lower level than you would normally use which the society would regard as a safe level," he added.