Ultrasound and Autism—A Connection?

Could ultrasound energy have an effect on the developing fetus?

Posted May 21, 2012

Could the increased use of ultrasound during pregnancy be implicated in autism?

That’s a question I discussed yesterday with University of Louisville researcher Manny Casanova.


A few stories have raised this question in recent years, but none have elaborated on the possible process, as he did for me yesterday. Here’s what he said:

"Ultrasonic energy is known to affect cellular membranes and cell growth. In fact, ultrasound is used as a therapy to accelerate bone growth following certain traumatic injuries. In stem cell research, ultrasound has been shown to accelerate development of cells. Knowing that stems cells are developing into neurons early in the fetal development, it’s quite possible that addition of ultrasound energy might shift that balance. The million-dollar question is whether the energy used during pregnancy exams is sufficient to have a possibly deleterious effect on a fetal brain. The original guidelines for ultrasound were conservative to protect against this, but evidence from the observation of current practice suggests current total exposure may be far higher than expected, for a variety of reasons."

Those were questions that I’d not heard before, when it came to ultrasound. The current and evolving view of autism is tht it comes from the combination of genetic predisposition (with hundreds of potential genetic markers) while being substantially influenced by environmental factors, (which could be almost anything.) Could ultrasonic energy be such an environmental influence, if delivered in the wrong spot at the wrong time? It seemed possible.

When I got back to my hotel room, I discovered a number of scientific papers supporting each of his points, but none really put the ideas together in the context of autism. I found that fascinating, and somewhat disturbing.

What I had heard were these questions:

Heating and vibration might also affect a fetus. Ultrasound will heat water, and the operation of ultrasonic cleaning systems is familiar to many of us. Either of those processes might affect fetal development adversely. To my surprise, I found the mechanism by which ultrasound speeds the repair of fractures is not fully understood, making it hard to evaluate those effects.

Like many people, I took for granted the idea that whomever approved ultrasound for clinical use made sure the power levels were low enough that the developing baby wasn’t cooked by its operation, or disintegrated like dirt on jewelry in the cleaning tank.

Not so fast, Manny cautioned me . . .

When ultrasound was developed, it was first used late in pregnancy, when all these risk factors are minimized. It was also used by trained staff and the machines, being new, were well calibrated. Most moms did not get ultrasound at all, and those who did typically received one or two.

The situation today is totally different. Many doctors do ultrasound much earlier in an effort to spot other problems, like Down’s syndrome. It’s common for moms to get three, four, or more ultrasounds done. Finally and most disturbing, many states have “ultrasound boutiques” in malls where moms can get ultrasounds as art; for the new baby scrapbook.

When the goal is a pretty picture, power levels may be turned up unwittingly. Safety is assumed by operators who are not always medical people, and who may have little knowledge of the underlying processes.

So we have the confluence of more ultrasounds, done earlier, and possibly with poorly calibrated equipment and inadequately trained people. I always associated ultrasound with professional staff in a hospital, but to hear Manny, it can be a lot more like a tattoo parlor experience.

In fact, several states have no regulation at all over the use of ultrasound imaging equipment. Anyone can buy it and make pretty pictures of your innards, perhaps cooking or altering you in the process. Do it yourself ultrasound gear is even sold online. In the hands of the wrong operator, it's like taking your developing baby and stepping into the microwave oven. That's something none of you would do, yet the mall ultrasound parlors reportedly do a brisk business.

Ultrasound Zeke has a wall full of beautiful fetal art, but it may have come at a high cost.

I hesitate to say that’s a frightening prospect, but it’s certainly one I’d study more carefully. If I were pregnant today, I’d be thinking hard if my doctor advised ultrasound early on, and I’d be reluctant to do it very often. If I did do it, I would seek out someone who had medical training and certification, with properly calibrated gear.

It’s temping to overreact to these things, and run from ultrasound, but I’m not suggesting that. For now, I am suggesting that we take a little more care when deciding when to do the test, and we do ultrasound only as needed, not for vanity. I further suggest we study the effect of ultrasonic energy on development of brains, especially those with known genetic predisposition to autism.

To recap: When ultrasound was first developed the tools were carefully calibrated, and operators received special training. The process was used sparingly, mostly late in the pregnancy.  Furthermore, not everyone received ultrasound at all. Today, the test is almost universal in many places. It's common for people to have four or more and they often begin earlier in the term.  Finally, the standards for calibration and use seem to have slipped, with the equipment being treated far more cauually. The result:  Moms today may be exposing their unborn babies to 10 or more times the total energy of moms at the inception of ultrasound. Therein lies the question of risk. 

When I discussed this earlier, some people jumped to the conclusion that I think ultrasound causes autism. I’m not saying that. I believe autism in various forms has been with us for a long time, far longer than ultrasound. However, that does not rule out the possibility that some developing fetuses in a vulnerable population may have been influenced by ultrasound energy. Knowing its effects, it’s perfectly reasonable question to ask. I hope we can answer it soon.

This is the second interesting question from IMFAR 2012. What are your thoughts?

John Elder Robison

Writing from IMFAR 2012

Toronto, Ontario, Canada