An independent study of the health effects of diagnostic ultrasound in pregnancy has concluded that there is no evidence that it poses any danger to unborn babies.

However, the independent Advisory Group on Non-Ionising Radiation (AGNIR) has advised caution regarding 'souvenir' foetal images.

The review, carried out for the Health Protection Agency (HPA), found no evidence that diagnostic ultrasound affects the mortality of babies during pregnancy or soon after birth, or that it affects childhood cancer risk. It notes, however, that unconfirmed reports suggest possible effects on the developing nervous system - for example, on handedness.

AGNIR concluded that while there is no established evidence that diagnostic levels of ultrasound pose any danger, further research is needed to determine whether there are any long-term adverse effects.

Professor Anthony Swerdlow, AGNIR chairman, said: "Ultrasound has been widely used in medical practice for 50 years, and there is no established evidence of specific hazards from diagnostic exposures. However, in the light of the widespread use of ultrasound in medical practice, its increasing commercial use for 'souvenir' foetal imaging, and the unconfirmed indications of possible neurological effects on the foetus, there is a need for further research on whether there are any long-term adverse effects of diagnostic ultrasound."

Following the report, the HPA has commented that parents-to-be should not hesitate to receive ultrasound scans for diagnostic purposes. However, they should consider the uncertainties when deciding whether to have ultrasound scans merely to provide keepsake images.

Justin McCracken, Chief Executive Officer of the HPA, said: "Overall, there is a track record of safety with diagnostic use of ultrasound, so people should continue using ultrasound for medical purposes. However, there are some uncertainties that need to be clarified through additional research."