Physicians have used ultrasound to make images of the inside of the human body for nearly half a century. Most infants now born in the United States were exposed to ultrasound before birth. And in Germany, Norway, Iceland and Austria, all pregnant women are screened with ultrasound. To date, researchers have not identified any adverse biological effects clearly caused by ultrasound, even while three million babies born each year have had ultrasound scans in utero (while in the womb). This is an enviable safety record.