WASHINGTON -- Exposure to ultrasound can affect fetal brain development, a new study suggests. But researchers say the findings, in mice, should not discourage pregnant women from having ultrasound scans for medical reasons.
When pregnant mice were exposed to ultrasound, a small number of nerve cells in the developing brains of their fetuses failed to extend correctly in the cerebral cortex.
``Our study in mice does not mean that use of ultrasound on human fetuses for appropriate diagnostic and medical purposes should be abandoned," said lead researcher Pasko Rakic, chairman of the neurobiology department at Yale University School of Medicine.
Women, however, should avoid unnecessary ultrasound scans until more research has been done, he added in a telephone interview.
Dr. Joshua Copel, president-elect of the American Institute of Ultrasound Medicine, said his organization tries to discourage ``entertainment" ultrasound, but considers sonograms important when there is a medical benefit.
``Anytime we're doing an ultrasound we have to think of risk vs. benefit. What clinical question are we trying to answer," Copel said in a telephone interview. ``It may be very important to know the exact dating of pregnancy, it's certainly helpful to know the anatomy of the fetus, but we shouldn't be holding a transducer on mom's abdomen for hours and hours and hours."
Rakic's paper said that while the effects of ultrasound in human brain development are not yet known, there are disorders thought to be the result of misplacement of brain cells during their development.
``These disorders range from mental retardation and childhood epilepsy to developmental dyslexia, autism spectrum disorders, and schizophrenia," the researchers said.
Their report is in today's edition of Proceedings of the National Academy of Sciences.
Early ultrasound scans are done to determine the exact week of the pregnancy, and they are also done later to check for anatomical defects and other problems.
However, some expectant parents have sought scans to save as keepsakes, even when they were not medically necessary, a practice the Food and Drug Administration discourages.
The Institute of Ultrasound Medicine was particularly concerned last year when it was announced that actor Tom Cruise had purchased an ultrasound machine for his pregnant fiancée, Katie Holmes, so they could do their own sonograms.
The research was funded by the National Institute of Neurological Disorders and Stroke.