prenatal exposure to ultrasound waves may not be safe, warn scientists who found it causes significant behavioural abnormalities in mice.

The researchers from the Yale Medical School in the us, said that when pregnant mice were exposed to ultrasound waves, the pups showed behavioural deficits. They have now called for similar studies on non-human primates.

The study found that ultrasound waves affect the area of brain called the cerebral cortex. It found doubling exposure time from 15 to 30 minutes almost doubled the effect while an exposure time to 420 minutes raised the effect four-fold. Exposure to ultrasound waves could also lead to epilepsy, warned the study published in Proceedings of the National Academy of Sciences (Vol 103, No 34, August 22, 2006).