Sunday, November 21, 2010

Are Ultrasounds Safe?

Ah, the ubiquitous ultrasound.

Ultrasound technology is spreading across the world like wildfire. Parents like it because they can "see" their baby, which makes the pregnancy and their connection to their baby feel more real. Doctors and medical staff like it because of the authoritative knowledge it confers upon them. (for more on this, see Robbie Davis-Floyd's Childbirth and Authoritative Knowledge: Cross-Cultural Perspectives)

Prenatal ultrasounds are used for confirming the pregnancy early on, figuring out gestational age, and checking for the location of the placenta. They can also be used to detect any fetal abnormalities, multiple pregnancies, and fetal position (the latter of which can also be determined using palpation).
Ultrasounds are also used to take measurements of the baby's size, which a computer then uses to guess at a weight (but as I have mentioned before here and here, this can be off by several pounds, so think twice before being talked into induction or c-section due to "big baby" diagnoses from an ultrasound).

What exactly is an ultrasound?
An  ultrasound uses high frequency sound waves which are transmitted through the mother’s abdomen and creates an “echo” where the sound waves bounce off the object (the baby!)
Most people don't question the safety of ultrasound, based on the fact that it is done so frequently (so it must be safe, right?). In reality, ultrasound was developed extremely quickly and not many random control trials have been done to determine its safety and even if its use is more accurate than other methods (such as examinations by hand, etc). It should also be noted that pregnant women were undergoing X-rays for 50 years to determine fetal size and pelvic proportion before it was discovered that this was causing birth defects and other serious side effects.

There have been a few studies on the safety of ultrasound, which I believe should be reviewed by anyone wishing to make an informed decision. 
While I personally believe ultrasound can have a purpose, the research below has me considering keeping the ultrasound visits to a minimum. 

Think Ultrasound for Babies Is Safe?

Research shows ultrasound populations have a quadrupled perinatal death rate, increased rates of brain damage, dyslexia, speech delays, epilepsy, and learning difficulties.
  • Perinatal death rate quadrupled in ultrasound group.  (2,475 woman study by Davies et al., 1993); Midwifery Today.
  • Ultrasound babies more likely to develop epilepsy and learning difficulties.  Ultrasound Abstracts.
  • Males babies exposed to two or more ultrasounds were 32% more likely to be lefthanded (which is thought to be caused by brain damage).  Ultrasound Abstracts.
  • Four hours after ultrasound, cell death doubles and rate of cell division drops by 22% in mammals and researchers believe results same in humans.  Ultrasound Abstracts.
  • Risk of miscarriage significantly increased among women who perform ultrasound more than 20 hours a week.  (Taskinen et al., 1990); Midwifery Today.
  • Babies who had serious problems and were ultrasounded died more often than non-ultrasounded babies with serious problems.  Midwifery Today
  • Ultrasounded babies who were growth retarded were three times more likely more likely to be admitted to ICU than non-ultrasounded babies who were growth restricted.  Midwifery Today
  • Preterm labor more than doubled in ultrasounded women.  (Lorenz et al., 1990); Midwifery Today
  • Researchers who developed ultrasound admitted possibility of hazard from ultrasound and said that it should never, ever be used on babies under three months.  Midwifery Today
  • Cells exposed to single dose of ultrasound behave abnormally ten generations after insonation.  Midwifery Today
  • Even if the above stats don’t give you pause, how about the fact that ultrasound measures 100 decibels in utero – that’s the equivalent of having your infant stand on a subway platform as a train comes roaring in and screeches to a halt  New Scientist.  As one writer notes, if you’ve ever heard of on opera singer breaking a sheet of glass with her voice, that is an example of what just one slow sound wave can do . . . but ultrasound uses ultra high frequency sound waves which bombard the child at an extremely high rate of speed.  New Scientist.
Perhaps most ironic and compelling is this quote from one of Yale’s MD elite (Dr. Kenneth Taylor, M.D., Professor of Diagnostic Radiology and Chief of the Ultrasound Section at Yale University School of Medicine) who states:  I would not let anybody get near my infant’s head with a transducer [ultrasound wand] . . .” A Prudent Approach to Ultrasound Imaging of the Fetus and Newborn by Kenneth Taylor, M.D.

Further References:
  • Beech, B. & Robinson, J. (1996). Ultrasound? Unsound. London: Association for Improvements in the Maternity Services (AIMS).
  • Bolsen, B. (1982). Question of risk still hovers over routine prenatal use of ultrasound. JAMA, 247: 2195-2197.
  • Donald, I. (1979). Practical Obstetric Problems. (5th ed). London: Lloyd-Luke, Medical Books Ltd.
  • Donald, I. (1980). Sonar—Its present status in medicine. In A. Jurjak (Ed), Progress in Medical Ultrasound, 1: 001–04. Amsterdam: Excerpta Medica.
  • Jahn, A. et al. (1998). Routine screening for intrauterine growth retardation in Germany; low sensitivity and questionable benefit for diagnosed cases. Acta Ob Gyn Scand, 77: 643–89.
  • Lorenz, R.P. et al. (1990, June). Randomised prospective trial comparing ultrasonography and pelvic examination for preterm labor surveillance. Am. J. Obstet. Gynecol, 1603–10.
  • Mason, G. and Baillie, C. (1997). Counselling should be provided before parents are told of the presence of ultrasonographic ‘soft markers’ of fetal abnormality (Letter). BMJ 315: 180–81.
  • Newnham, J.P. et al. (1991). Effects of frequent ultrasound during pregnancy: a randomized controlled trial. The Lancet, 342: 887–90.
  • Saari-Kemppainen et al. (1990). Ultrasound screening and perinatal mortality: controlled trial of systematic one-stage screening in pregnancy. The Lancet, 336: 387–91.
  • Salvesen, K.A. et al. (1992). Routine ultrasonography in utero and school performance at age 8–9 years. The Lancet, 339.
  • Skari, H. et al. (1998). Consequences of prenatal ultrasound diagnosis: a preliminary report on neonates with congenital malformations.
  • Tarantal, A.F. et al. (1993). Evaluation of the bioeffects of prenatal ultrasound exposure in the Cynomolgus Macaque (Macaca fascicularis). Chapter III in Developmental and Mematologic Studies, Teratology 47: 159–70.
  • Taskinen, H. et al. (1990). Effects of ultrasound, shortwaves, and physical exertion on pregnancy outcome in physiotherapists. Journal of Epidemiology and Community Health 44: 196–201.


  1. Wow! I am completely appalled! I had 3 or 4 of these when I was pregnant! Never, never again! Now if my son has a speech delay or a learning disability I will forever look back to those times I had ultrasounds. We should be able to sue for stuff like this! Seriously.....4 ultrasounds and not even 1 is completely safe!!! UGH!!

  2. Hey so I'm sitting in class learning about Ultrasound, and I remembered this post and went back to look at it because it completely contradicts what I'm learning in class, and Emily, I looked up these articles.. some of them don't exist, some that do are not in peer-reviewed journals, and the ones that ARE in peer-reviewed journals actually show POSITIVE benefits of ultrasound, that they reduce perinatal mortality, that they give you earlier detection of pregnancy complications. The one article that Dr. Taylor from Yale wrote was not talking about therapeutic ultrasound at all, but rather experimental ultrasound for detecting brain waves, which uses 100x the beam that an OB/GYN would use to look at babies normally. He was saying investigators shouldn't be so chivalrous and assume ultrasounds are completely noninvasive so do crazy things during experiments.

    So actually in retrospect I don't think I believe this post.. I think you'd be doing some disservice to the people who read your blog if you advise them against ultrasound.

  3. yikes, i'm left-handed.....and life is pretty rough. Look, you need to be a bit more deliberate in letting people know that your findings are based on your own biases and were not researched fully enough to be considered as fact. This type of information is disseminated too broadly for it to be posted so haphazardly. I appreciate the right to an opinion but please be more clear. You have a great blog that can do more to help but this is going to hurt your credibility if you have the intent of being a reliable source.

  4. I think ren makes some excellent points, and here's another that she/he didn't mention:

    Even if any of those studies are valid and in peer-reviewed journals, most of them are 20yrs old or more. The latest date I noticed was 1998. These publications are out of date, and odds are that more recent data can be found. I guess the question would be: Would more recent data support your argument? I am suspecting the answer would be "no" since there isn't any here.

    Oh and correlation does not equal causation. If a baby/babies are discovered (by u/s) to have some complication, likely they will have more u/s to track said complication. And more babies with complications (and therefore, more u/s) end up in NICU or with short or long term issues.

    For example, there are known issues that tend to go along with prematurity, like CP, blindness and developmental delays. More than half of all multiples are premature. Women carrying multiples tend to get more u/s than women carry singles, but regardless of u/s, multiples simply tend to be preemies. Their prematurity is WAY more strongly associated with (and thought to be causative of)the complications mentioned above than u/s or any screening procedure.


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