I’m always amazed at the way expectant mothers are able to interpret the images of their ultrasounds. What look essentially like grey and black blobs to me suddenly become hands, fingers, faces and knees to these excited women. I stare at the pictures and try to assign body parts and characteristics. As it gets closer to the delivery, I am better able to recognize the features and can really see the baby. I see its little face and even start seeing a “personality.” It is truly astonishing to be able to see a baby months before it is born. Seeing the detail, however, and the frequency with which mothers get these scans makes me wonder just how safe ultrasounds really are. Most mothers have multiple ultrasounds performed throughout the course of their pregnancies. Some even have their bellies scanned each time they have a prenatal visit. None seem at all concerned about the sound waves they are exposing their baby to or the impact these tests may have on the developing fetus.  Instead, they are thrilled at each opportunity to view their growing baby and feel relieved each time they see its fluttery little chest on the screen. Is this really how doctors should be handling these tests? Is it safe to have so many ultrasounds during pregnancy?

Little research has been done into the true impact of repeated ultrasound imaging on a developing fetus. One study, however, involved two groups of women selected randomly to participate either in an intensive group or a normal group. In the normal group, participants received one ultrasound scan at 18 weeks. This is usually considered the “anatomic development” scan and is the point at which the growing baby is checked to ensure it is developing properly. The intensive group received scans five times during their pregnancies, at 18, 24, 28, 34 and 38 weeks. The results showed only one difference between the babies born to these women. Women in the intensive group experienced dramatically higher instances of intrauterine growth restriction than those women who were in the normal group. Though not enough evidence has been gathered to make an absolute correlation, these results do indicate that an increased amount of ultrasound and Doppler flow exposure could have a negative influence on fetal growth. To be on the safe side, many experts now are recommending that doctors limit ultrasound imaging only to those patients who would have a distinct clinical benefit from such testing.

Source: Prof J.P. Newnham. Effects of frequent ultrasound during pregnancy: a randomised controlled trial. The Lancet. Volume 342, Issue 8876, 9 October 1993, Pages 887–891

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