Keepsake ultrasounds 'may harm unborn child'

By Roger Highfield, Science Editor

(Daily Telegraph: 08/08/2006)

An American research team emphasises that the benefits of ultrasound for diagnosing problems in pregnancy still outweigh these potential risks, which have yet to be confirmed in human studies. But even though the study, by Dr Pasko Rakic at the Yale School of Medicine, used rodents, his team says it raises concerns about the non-medical use of ultrasound, where low intensity waves are used to take images of the unborn child.

They have been touted as a way to help relieve parental fears that an unborn child may have a deformity.

Businesses with names such as Womb with a View, A Peek in the Pod and Fetal Moments have appeared across America and in Britain there is The Baby Ultrasound Company and BabyPremier.

Tom Cruise went a step further and bought an ultrasound machine to gaze at his unborn child.

Dr Rakic's study of more than 300 foetal mice showed that ultrasound can disrupt the way in which the brain wires itself up.

"A small but significant number of neurons in the mouse embryonic brain do not migrate to their proper positions in the cerebral cortex following prolonged and frequent exposure to ultrasound," he says.

"The magnitude of dispersion of labelled neurons was highly variable but increased with duration of exposure to ultrasound waves," says Dr Rakic, the chairman of the department of neurobiology and senior author of the study published in the Proceedings of the National Academy of Sciences.

Prof Denis Noble of Oxford University , the chairman of a group studying the medical use of ultrasound for the Health Protection Agency, welcomed the research and said surprisingly little has been done to study the effects of ultrasound on the foetus.

He said he did not approve of the use of ultrasound for entertainment or souvenirs. "I would regard this as largely unnecessary and, given how little we know, perhaps people should not do it."

Diagnostic ultrasound uses low intensity waves to generate images, unlike X-ray which requires ionizing radiation, a potential carcinogen. But ultrasound energy delivered to the foetus cannot be regarded as completely innocuous.

Even before today's report, laboratory studies showed that diagnostic levels of ultrasound can produce physical effects in tissue, such as mechanical vibrations and rise in temperature, effects that are now being studied by Prof Noble's group.