The type of ultrasound used to scan babies in the womb disturbs brain cells in mouse fetuses, say researchers. The finding fuels a debate about the safety of the technique for unborn babies. Babies in the womb are routinely scanned using high-frequency sound waves. The scans allow doctors to check on growth rates and spot developmental abnormalities.
Pasko Rakic of Yale Medical School in New Haven, Connecticut and his team were similarly scanning experimental mice, to help inject dye into embryos. When later studying the brain development of these mice, the team noticed that certain neurons in the growing cortex were not behaving normally. Rakic says that he has no evidence that ultrasound scanning disrupts the brains of human fetuses. The affected mice in his study were exposed to continuous ultrasound for 30 minutes or more; a baby’s brain would be exposed for only a fraction of this time during a 30-minute scan of its entire body. And a narrow ultrasound beam will hit and affect far more of a small mouse brain than a larger human one.