Are Prenatal Ultrasounds Dangerous?

Several questionable sources are spreading alarms about the possible dangers of prenatal ultrasound exams (sonograms). An example is Christine Anderson’s article on the ExpertClick website. In the heading, it says she “Never Liked Ultrasound Technology.”

[She] has never been sold on the safety using Ultrasounds for checking on the fetuses of pregnant women, and for the last decade her fears have been confirmed with a series of studies pointing to possible brain damage to the babies from this technology.

Should We Believe Her?

Should we avoid ultrasounds because Anderson never liked them? Should we trust her judgment that her fears have been confirmed by studies? Who is she?

“Dr.” Christine Anderson is a pediatric chiropractor in Hollywood who believes a lot of things that are not supported by science or reason. Her website mission statement includes

We acknowledge the devastating effects of the vertebral subluxation on human health and therefore recognize that the spines of all children need to be checked soon after birth, so they may grow up healthy.

It also states that “drugs interfere… and weaken the mind, body, and spirit.” Anderson is a homeopath, a craniosacral practitioner, a vegan, and a yoga teacher. She advises her pregnant patients to avoid toxins by only drinking filtered water and only eating organic foods. She sells her own yoga DVD.

In her own pregnancies she refused ultrasound and other prenatal screening tests. This was her idiotic reasoning:

I trusted in my body’s innate wisdom that if the pregnancy was moving forward, then everything was going OK in my baby’s development.

Apparently on her planet if a pregnancy has not spontaneously aborted that means the baby is developing normally, and no abnormal child is ever born. And perhaps all the children are above average?

She believes in many alleged benefits of chiropractic that are not substantiated by any evidence. She says that our emotions create chemical changes in our bodies that can affect our developing babies; and that chiropractic helps to keep those feel good chemicals flowing freely. She believes that chiropractic frees up any interference to the nervous system and since the nervous system controls all the functions in the body, chiropractic manipulations allow the organs to optimally process any toxins they encounter. She believes getting regular chiropractic care reduces labor times.

Based on this, I am not impressed by her medical judgment or her understanding of biology or science, but that doesn’t necessarily mean she is wrong about ultrasound. What does she say?

Alleged Risks of Ultrasound According to Anderson

  • Ultrasound heats the tissue and researchers suspect that the waves cause small local gas pockets which vibrate and collapse called cavitation. The gas can reach up to temperatures of thousands of degrees (Celsium) [sic] leading to production of potentially toxic chemical reactions.
  • Studies done on mice have shown intestinal bleeding caused by changes in the cells. Scientists conclude that there would be similar effects in humans.
  • Ultrasound has been linked to the following abnormalities:
    • Left handedness in children who are supposed to be right-handed. Although there is nothing inherently wrong with being left handed, the change is attributed to a subtle damage to the brain. Males are more affected than female fetuses, probably because the male brain develops later.
    • Early labor, premature birth, miscarriage, low birth weight, poorer health at birth, and perinatal death.
    • Increased learning disabilities, epilepsy, delayed speech development, dyslexia

She also alleges that no studies have been done to prove the safety of these devices. This is demonstrably false.

Elsewhere, prenatal ultrasound exposure has even been accused of causing autism although a study found no association.

Risks According to Scientists

Obstetricians and radiologists who have evaluated the peer-reviewed literature have found no evidence of harm except for an apparent correlation between ultrasound exposure and left-handedness (in males only!).  Such odd-sounding correlations are usually not significant, and are mostly good for a chuckle.

Experts place little reliance on the mouse studies, since the dosages tested were higher than what humans are exposed to and since no corresponding clinical consequences have been detected in humans. Nevertheless, they acknowledge theoretical reasons for concern, and they recommend that medically unnecessary ultrasounds be avoided under the precautionary principle.

Does Routine Ultrasound Affect Outcomes?

A large study (15,530 women) published in The New England Journal of Medicine found that routine screening did not reduce perinatal morbidity and mortality.  There were no significant differences in the rate of preterm delivery, distribution of birth weight, or outcomes within the subgroups of women with multiple gestations, small-for-gestational-age infants, and post-date pregnancies. Finally, the detection of major anomalies by ultrasound examination did not alter outcomes. The authors pointed out that routinely screening more than 4 million pregnant women annually in the United States at $200 per scan would increase costs by more than $1 billion.

A Finnish study found that perinatal mortality was significantly lower in the screened than in the control group (4.6/1000 vs 9.0/1000); but this was attributed to improved early detection of major malformations which led to induced abortion. All twin pregnancies were detected before the 21st gestational week in the screening group compared with 76.3% in the control group; perinatal mortality in the small series of twins was 27.8/1000 vs 65.8/1000, respectively.

Caveats: These studies did not look for long-term consequences like learning disabilities. And there are other considerations besides morbidity and mortality. Ultrasound can reassure patients or allow them to plan ahead for multiple births or abnormal infants, and it can guide obstetric management.

Reasons for Doing Ultrasounds

Ultrasounds can detect fetal abnormalities and can help guide obstetric care by detecting problems like multiple fetuses and placenta previa. There are many legitimate reasons for doing them, especially in high-risk pregnancies or when a specific problem is suspected.

Reasons for Not Doing Routine Ultrasounds

False alarms can be raised. Apparent abnormalities may cause worry but turn out not to be significant. Placenta previa detected early in pregnancy frequently resolves before delivery.

There is no way to completely rule out the possibility of a low risk of long-term consequences. Trying to identify such consequences by even the most careful epidemiologic studies is fraught with pitfalls, since if you look for every possibility you will inevitably find a few spurious correlations. Experts agree that routine ultrasound screening is not necessary in low-risk pregnancies and that ultrasounds for nonmedical reasons should be discouraged.

Some nonmedical uses are particularly objectionable. Ultrasounds are being used in India and elsewhere to determine sex for the purpose of aborting undesired female fetuses.  Ultrasound is being commercially promoted for “keepsake” pictures and movies like this 5 minute video. Tom Cruise was roundly criticized by doctors for buying his own ultrasound machine for home use.


There is no reason to fear prenatal ultrasounds that are ordered by science-based medical professionals and performed by qualified technicians, but it seems prudent to exercise caution and not do them for frivolous reasons.

Considering that Anderson practices homeopathy, subluxation-based chiropractic, and craniosacral therapy, disparages drugs, and manipulates the spines of newborn infants, I think her own practices are far more worrisome than the ultrasounds she fears.




Posted in: Diagnostic tests & procedures, Obstetrics & gynecology

Leave a Comment (57) ↓

57 thoughts on “Are Prenatal Ultrasounds Dangerous?

  1. clare_hendry says:

    If one thinks of how many mothers and babies have been saved as a result of ultrasound technology, I would be prepared to accept a significantly higher risk to protect myself and my child.

    Anyway, if this were true, we would be seeing significant increases in learning disabilities and brain damage as countries become increasingly developed. And that is simply not true.

  2. windriven says:

    “[N]o evidence of harm except for an apparent correlation between ultrasound exposure and left-handedness (in males only!).”

    What is the differential incidence of sinistromanuality in ultrasound / non-ultrasound populations?

  3. Sabio Lantz says:


    I trusted in my body’s innate wisdom that if the pregnancy was moving forward, then everything was going OK in my baby’s development.

    I am an ex-Homeopath and ex-Acupuncturist. This logic permeate much of alternative medicine and is very wrong. Experience teaches that — unless one is very lucky.

    You go through re-assuring us that the mice experiments don’t mean anything, that left-handed issues are just odd. Then you tell us not to do US for “non-medical reasons” but the reasons you give are cost and unnecessary worry. (which I agree with)

    We have our own U/S tech in our office (Urology) and pregnant staff are getting U/S frequently for monthly “my cute baby” scrapbooks.

    So there is not cost to them and there is no unnecessary worry for the most part (just unnecessary obsession). So my question: at what point do you think too much U/S is too much for physical health reasons. Is that question important? Or are all your reasons essentially social (cost) and psychological?

  4. Sabio Lantz says:

    PS – Thank you kindly for the article!! I learned a lot. This site has very generous authors.

  5. AlexisT says:

    Sabio: The other concern is those places in malls who offer “fun” ultrasounds–the ones that say “not for diagnostic purposes.” In my mind, that’s both frivolous and potentially hazardous, since (AIUI) these places are not regulated.

    I have never worried about my numerous ultrasounds or non-stress tests other than the possibility of a bad result, but something about the casual use of ultrasound rubs me the wrong way. I don’t really like the “we don’t know if it’s 100% safe” argument, since it skews close to the “If we don’t know it’s safe for sure, we shouldn’t do it!” argument. But it does seem to me like we should treat a medical technique with a little bit of respect. Maybe it’s just because I don’t get the luxury of treating these tests casually (those twice a week NSTs are one of your less fun uses of the technology…)

  6. Enkidu says:

    I was high-risk and had over 20 ultrasounds for a pregnancy that ended up being only 27 weeks long (but am happy to report ended in a little girl now 3 years old and healthy). I researched the risks of ultrasound along the way and could find none in my pubmed wanderings aside from mouse studies (as mentioned above).

    What I can say from my experience though, is that when things are going wrong in pregnancy (I had bleeding throughout) there is nothing that will calm a woman’s fears like seeing her baby alive and well by ultrasound.

  7. Ultrasounds find many children that will be born with cleft lip and palate. I believe this is beneficial to both the parents in the child, since it allows the parents time to acclaimate themselves emotionally to the idea of the child’s difference and see it for the treatable, managable condition that it is.

    It allows parent’s to take time during the later prenatal period to prepare for differences in feeding and familiarize themselves with the cleft team options in their area. Once parents are familiar with the treatment, standard care for children with clefts and have spoken (in person or online) with other parents of children with clefts they are free to enjoy the birth and infancy of their child much more fully than if they were presented with the cleft at birth. It seems to me this would result in healthier children and parents, but I’m not sure what the research (if any) indicates.

  8. Costner says:

    Well thank you Ms. Anderson (I can’t bring myself to call you a Doctor) for suggesting that because I am left handed that I must be defective. I realize you didn’t use the actual term “defective”, but when you suggest being left handed is due to “subtle damage to the brain”, you are essentially telling me I am brain-damaged.


    I wonder if there is a Chiropractic treatment that could fix my condition and allow me to find my true inner right-handedness that I have been missing for almost four decades.

    Seriously… how to people continue to fall for this garbage? It reminds me of the old George Carlin quote – “think about how stupid the average person is, and then realize that half of ‘em are stupider than that”.

  9. @costner, being left handed I had the same reaction. But what really got me was the ‘left-handedness in children who were supposed to be right-handed’ comment. How, exactly, do you figure out that a child was ‘supposed to be right-handed’?

    I wonder if there’s some interesting tests and ‘treatments’ behind that phrase.

  10. CarolM says:

    Gee, and to think of all the creative high-achievers who are left handed..makes me as a righty feel dreadfully average. How could left handedness prossibly be a curse.

  11. CarolMon 30 Aug 2011 at 11:21 am

    “Gee, and to think of all the creative high-achievers who are left handed..makes me as a righty feel dreadfully average. How could left handedness prossibly be a curse.”

    It can be a bit of a drag to live in a right handed world, right-handed spiral notebooks, right handed desks and the whole writing left to right, were always my pet peeves… guess they just don’t make curses like they used to. :)

  12. Harriet Hall says:

    @Sabio Lantz,
    “you tell us not to do US for “non-medical reasons” but the reasons you give are cost and unnecessary worry.”

    No, the reasons experts give for not doing unnecessary ultrasounds are the concerns raised by the animal studies, the possibility of localized overheating, etc. I think everyone agrees that any risk would be minimal even in the worst case, but because of the precautionary principle, most doctors think it is better to avoid even a minimal possible medical risk if there is no medical benefit.

  13. Cool post. when CAM has a problem with ultrasound, you just have to ask, ‘what next.’ They could ban the giving of teddy bears and cards at the delivery room.

    There is nothing wrong with being left-handed. However, it can happen that a neurological insult can lead to a subtle developmental problem which will manifest itself in various ways, and one of those is left-handedness. The left-handedness is just a sign of the harm. Analogy: Some people have slow-growing hair, and others fail to have hair growth due to radiation exposure. Baldness is not a problem in itself, but is present with enough radiation exposure.

    The problem with ultrasound is when it is used to detect reasons for abortion. Some in the disability-rights movement are bothered that pre-born children are being aborted merely for having a prenatally diagnosed birth defect, including cleft palate.

    Ultrasound is being used to determine whether the pre-born baby is male or female, so gender selection by abortion can be practiced: a resercher “G Lin” presented “Low Female-Male Birth Gender Ratios Become More Widespread in California as Keepsake Ultrasound Proliferates” at the 2011 American Institute of Ultrasound in Medicine Annual Convention.

    Ultrasound is practically invaluable for prenatal surgery. Prenatal surgery is an amazing growing field.

    If ultrasound itself harmed the developing human in utero, there would be smoe kind of signal to discern at this point. It would be valuable data to have resch done on mice to figure out the degree that repeat ultrasound, up to some level like double the number of sessions a human might get in some extreme circumstance, at whatever might be the full power.

  14. icewings27 says:

    The idea that our bodies have some sort of “innate wisdom”, along with the myth that all low-risk pregnancies end in a live birth and a healthy baby, both need to die.

    My first son died the day before his due date because the midwife didn’t want to do an “unnecessary” ultrasound at 38 weeks even though I measured 4 weeks small.

    My second son had oligohydramnios – diagnosed at 34 weeks during one of many weekly ultrasounds – and labor was induced at 38 weeks, when the levels went down to 2cm. He was born healthy. He is right-handed btw. I am convinced my first son died of some complication resulting from oligohydramnios, which would have been detected on an ultrasound, and he would be alive today.

    I think one ultrasound per trimester should become routine. And the next woo advocate who tells me to trust nature’s wisdom is going to get slapped. Nature delivers stillborn babies.

  15. daedalus2u says:

    Don’t chiropractors like to take full body skeletal x-rays like they are going out of style? Kind of curious that Christine Anderson denigrates the use of ultrasound but endorses and uses x-rays prior to most chiropractic treatment to “treat” what is certainly a non-medical condition, bad subluxations.

    I was curious as to the ultrasound left handed result and found this abstract.

    I looked and didn’t find very much on the incidence of left-handedness in the population, but some that indicates pretty strong season of birth effect. There is also some sparse data on how the incidence has changed over time.

    Humans are mostly bilaterally symmetric. There are important asymmetries in many of the major internal organs, brain, heart, gut, liver. Presumably there are symmetry breaking events at certain critical times in utero that produce these asymmetries. Characteristic symmetry breaking needs a characteristic asymmetric signal of the right length scale at the time of symmetry breaking. Presumably that length scale is on the order of a few microns, the size of one or a few cells.

    The sound used is on the order of 5.8 MHz, so the wavelength in water is ~ 260 microns. When the sound reflects from internal structures, the reflection does put an asymmetric signal on what ever structures are doing the reflecting, but it is kind of hard to imagine what physiology would do that. I am pretty sure it would have to depend on fetal orientation to the ultrasonic signal.

    Left-right-handedness symmetry breaking is probably pretty subtle if there is a significant effect of season of birth on it and if it has changed significantly in the past several hundred years.

  16. Amy (T) says:

    “no evidence of harm except for . . . left-handedness (in males only!). Such odd-sounding correlations . . . are mostly good for a chuckle.”

    which I had. my husband and I are both left handed, and as our daughter indicated being left handed, I guess I’m suppose to wonder is it genes or US?

    personally, I loved having the US, it was just amazing. for every low-plausibility, small correlation-only child out there with a learning disorder the mother claims unscientifically on the US, there are how many other babies (way more) who would have benefited from one or more US? My friend recently lost her premature baby; she had a number of risk factors, and a 2nd US a few weeks after her 20 wk one would have shown the failing placenta and no fluid. it’s anecdotal, and we don’t know the outcome if she had been screened again, but all those mothers in 3rd world countries could sure benefit from having one.

  17. “The problem with ultrasound is when it is used to detect reasons for abortion. Some in the disability-rights movement are bothered that pre-born children are being aborted merely for having a prenatally diagnosed birth defect, including cleft palate.”

    Medvstherapy, do you have any sources to support this statement?

    I’m not aware that aborting due to a diagnoses of cleft lip and palate alone happens in the U.S.. One consideration, I believe*, is that clcp is not diagnosed on ultrasound until the second trimester.

  18. Harriet Hall says:


    Any historical comparisons of left-handedness rates must take into account that left-handedness was stigmatized and it used to be customary to discourage left-handedness by forcing children to use their right hands.

  19. Woody says:

    “Elsewhere, prenatal ultrasound exposure has even been accused of causing autism although a study found no association.”

    As a parent of twins with autism, I wondered about the possible impact of the frequent prenatal ultrasounds our children were exposed to in utero. In our case, frequent ultrasounds were necessary not only because of the twin pregnancy, but also because my wife developed cervical incompetence necessitating a cerclage and bedrest the last few months of the pregnancy.

    I think there is published data on a higher incidence of autism in twin pregnancies, and in our case there were other obvious factors that could have influenced neural development aside from the frequent ultrasounds. The study Dr. Hall linked to did not look at “high risk” pregnancy or multiple gestations, so I would say the jury is still out for those populations.

    Certainly the wealth of the data in the literature for the etiologic basis of autism suggests strong genetic factors, though I would agree with the points raised by daedalus in numerous threads that there probably are important gene-environment interactions that dictate the phenotype.

    I will say this – if we hadn’t been getting the frequent ultrasounds, we probably would have lost both of our children. My wife was completely asymptomatic when the cervical incompetence was detected. In retrospect, would I have changed anything? No way.

  20. AlexisT says:

    Michele: Anecdotally, I am aware of 2 cases where parents aborted for cleft lip and palate. This proves absolutely nothing about frequency, but I also doubt I managed to hear about the only two cases. OTOH, I know people who had it prenatally diagnosed, and did not abort. I certainly don’t think it’s like Down Syndrome, where people who are unwilling to abort seem more likely to avoid screening (they may know about the presence of soft markers on ultrasound, but don’t do testing/screening specifically aimed at DS and other chromosomal abnormalities).

  21. icewings27 says:

    @Medvstherapy –
    In the United States and many other developed nations, abortion is legal up to 24 weeks regardless of the reason. You can have an abortion because the baby has a defect, or because it is an undesired gender, or because you can’t afford it, etc. Aborting a baby after finding out it has cleft palate or any other defect is just as legal as aborting a “normal” baby for any other reason.

    So, arguing that using ultrasound to detect birth defects and soft markers for genetic syndromes might lead to abortions is a moot point. Abortion is legal no matter whether you approve of a woman’s reason for doing it or not. That’s why it’s called a choice.

  22. AlexisT – huh, go figure. Are you a healthcare worker or something? Knowing several people with ultrasound diagnoses of cleft lip and palate would be kinda a strange occurrence otherwise. 1 in 700 children being born with cleft lip and/or palate, it doesn’t come up often with just general social exposure.

    Of course, I’ve seen a lot of kids with cleft lip and palate, due to taking my son to his cleft clinic. They seem to have lots of patients and lots of happy parents there.

    Regardless, I can’t see withholding important information that responsible parents will find useful to prepare for their child’s care so as to avoid a potential abortion decision. If one is concerned about the abortion fetuses with malformations, parent education, accessibility to needed health care and educational support services are the main fixes in my book.

  23. nybgrus says:

    @d2u: Random tidbit for you – the developmental asymmetries arise early on when the meshenchymal cells migrate through the embryonic plates. They arise because cilia all rotate in the same direction, imparting an angular momentum on the cells as they migrate. This is why in Kartagener’s syndrome there is often situs inversus, because they lack ciliary motility.

  24. Jann Bellamy says:

    It is interesting that a chiropractor, who is forbidden by law in California from practicing obstetrics, deems herself a sufficient “expert” to hold forth on the advisability of an ultrasound during pregnancy. The website cited in her “expert” opinion on ultrasound also contains information on the “Webster Technique,” a bogus chiropractic procedure which purports to turn a breech baby. (In addition to anti-vaccination misinformation.)

    “Don’t chiropractors like to take full body skeletal x-rays like they are going out of style? Kind of curious that Christine Anderson denigrates the use of ultrasound but endorses and uses x-rays prior to most chiropractic treatment to “treat” what is certainly a non-medical condition, bad subluxations.”
    I happen to have a copy of a chiropractic textbook, “Pediatric Chiropractic,” Anrig C, Plaugher G eds, Lippincott Williams & Wilkins (1998), which contains a chapter, “Diagnostic Imaging.” It contains a number of x-rays of infants and children supposedly demonstrating the chiropractic “subluxation” and supports the use of x-rays of pediatric patients to detect the non-existent chiropractic subluxations.

  25. daedalus2u says:

    Harriet, I am aware that there was a great stigma against left handed individuals. I remember a case from fifth grade where a student who had terrific handwriting with his left hand and which slanted to the left was failed by his teacher because she wanted it to slant to the right. It was senseless bullying of someone who was left handed.

    I found this very interesting paper on symmetry development in frogs.

    This next paper shows the acoustic waveform (figure 2) that is typically used in prenatal ultrasounds.

    It is interesting that the 5.8 MHz pulses are repeated at ~9 Hz. That puts power at a 9 Hz frequency. If that is close to the frequency that disrupts left-right symmetries, that might be the problem. If so, it might be possible to mitigate that problem just by dithering the frequency of repetition or interrupting it so the number of contiguous pulses isn’t that long.

    If there is a disruption of left-right symmetry breaking by exposure to ultrasound, it is likely that is is only the left-right symmetries that are being determined at and during the specific time of the ultrasound would be affected.

    I suspect (but this is quite speculative), that there are many asymmetry breaking events in utero, and that these lead to the asymmetric patterning of the brain and other organs, none of which are particularly symmetrical. In the brain, that may lead to the idiosyncratic differences in personality.

    Autism happens quite early, during the first trimester, so ultrasounds later couldn’t be causal. The most characteristic symptom is more minicolums and that number is fixed at ~8 weeks (as I remember).

    Exposure to vibration does cause production of nitric oxide. Dr Novella has a very recent post over at Neurologica on how vibration causes release of calcium (in the context of acupuncturists claiming their needling has effects via this mechanism). Calcium gradients are used for axon targeting, so vibration could screw it up, but only axons that are homing in during the time of the ultrasound. Changes in that homing and patterning are necessarily “damage”, just differences. Differences in axon homing and patterning are what make each individual unique.

    It is probably very safe, but like anything, if you don’t need it, not doing is safer still.

  26. Anthro says:

    I found this toward the end of the referenced article and would love for someone to debunk this–I know its ridiculous but can’t put it into words.

    “To give you some means of comparison, I offer this analogy. Have you seen a woman with an extremely high voice break a glass by singing an extremely high pitched note? That is an example of what just ONE relatively slow sound wave can do. Ultrasound technology is based upon ultra high-frequency sound waves, which bombard the child in the womb at an extremely high rate of speed. If one slow sound wave from a woman’s voice can break a glass, what can super high frequency sound waves do to your child? Ultrasound waves in laboratory experiments have been known to damage chromosomes, produce internal cellular heat which damages cells, retard the normal development of cells, and many other phenomenon. “

  27. Amy (T) says:


    in Oklahoma, as I understand it, our legislature has outlawed abortions based on sex.

    As for aborting because of cleft lip, sex, or severe abnormality, if it’s under 22 weeks, it’s up to the expecting parents. My personal opinion is no child should come into the world unwanted, so if a parent doesn’t want the child, why should they carry on with the pregnancy? (Of course I would like society accept the sex spectrum and differences, but that still doesn’t mean a woman should have to carry, birth and raise and unwanted child (my opinion).

  28. Harriet Hall says:


    False analogy.
    Have you ever seen a soprano shatter a frog or a tomato?
    A glass has a resonant frequency. A frog doesn’t. Neither does a tomato, a chromosome, or a cell.

  29. nybgrus says:

    What Dr. Hall said, plus the amplitude of the waveform is quite different. In fact, it is exceedingly difficult to break the glass without electronic amplification since even though the glass resonates most human voices can’t generate enough amplitude (energy) to get it to resonate enough for structural damage to occur.

    Also, the frequency that the glass resonates with changes with the type of glass used. So indeed, some glasses may need a low frequency as “Dr.” Anderson claims, but some may require much higher frequencies.

    So yeah, just a completely wrong analogy.

  30. nybgrus says:

    of course, we may have just opened up a can of worms….

    Dr. Hall – your comment got me thinking:

    Neither does a tomato, a chromosome, or a cell.

    And I found a paper demonstrating that chromosomes in metaphase do have a resonant frequency (22-50kHz) and that actually can be used to disrupt mitosis. It makes sense – they are physical entities on a string which can vibrate and are subject to Brownian forces anyways so…. yeah. The paper is geared towards potential use for disrupting neoplastic mitoses – which sounds very interesting indeed. Of course, that frequency is far below US frequencies, so it would have no bearing in our case. I just hope that it doesn’t become quote mined for support of such a claim as “Dr.” Anderson is making.

    Although I did find this site that talks about such resonant frequencies. I haven’t had a chance to read it and figure out exactly their slant and I won’t till later today since I am about to head off for a nice 75km bike ride as it is a gorgeous day today.

    I’m not disputing that the analogy is false, just picking a nit for a bit of scientific interest. If any of the esteemed commentariat here find themselves keen to take a gander and give their impression I’d be curious to read. Otherwise I will probably do it myself anyways when I return. :-)

  31. nybgrus

    “of course, we may have just opened up a can of worms”

    …as long as the worms aren’t in a glass can they should be fine. :)

    Sorry, I just was overwhelmed with the vision of a bunch of worms worriedly gazing at the soprano, who has just opened their can. This is the kind of thing that happen to you when you are a brain damaged left-hander.

  32. Harriet Hall says:


    I stand corrected. You can pick my nits any time. :-)

  33. daedalus2u says:

    Resonance as a factor in damaging something is only relevant when energy is being added faster than it is being dissipated, that is the system is taking energy from the vibration, storing it, until the magnitude of the energy being stored is so high that the material fails.

    In the case of a glass in air, air is essentially a dissipation-free material, so the glass can pick up energy every cycle, store it, and continue to pick it up until it breaks. This requires several things which do not hold for biological systems and for ultrasound.

    All structures in organisms are in water, which is a high mass and high dissipation material. The frequency of the sound used in ultrasound is not at a resonant frequency of any structural components of organisms, and if it was, the resonant frequency of the structure would change as the amplitude of the vibration changes (the resonant frequency of the glass stays the same until it breaks). Also, the way that ultrasound is used, is as pulses of a few waves. There isn’t time for a “resonance” to build up because there are only a few waves in the signal. This is illustrated in one of the papers I linked to above.

    For the glass, if it takes a few seconds at a few kHz, that is several thousand cycles. At resonance, the little energy that is picked up each cycle gets stored and added to by the next cycle. If there is dissipation, or if there re only a few cycles, (or both) resonant damage can’t happen.

    You can get resonances if there are bubbles present, and the right size bubbles can resonate at the frequencies being used. They use artificial bubbles like that as ultrasonic contrast agents and they do increase the damage where they are used because there is local resonance and local amplification of energy dissipation. This would show up as a bad noise on the image.

    In general there is only damage where there are air-liquid interfaces. There aren’t any in utero, the fetus is gas-free. The lung and the bowel are the two tissue compartments that are most vulnerable to ultrasound because they have air voids. It is the large change in acoustic impedance at a liquid-air interface that causes high energy dissipation. You can see that on films of underwater explosions. When the shock-wave hits the surface it is reflected and causes the surface to cavitate. The surface goes white when the shock hits it and is reflected back down.

    You have to remember, this discussion of vibration is coming from a Homeopath. They have strange and completely non-physical ideas about what vibration is, how it is generated and how long it can persist. They think that vibrating water can have effects even when put on sugar pills and evaporated.

  34. nmarasigan says:

    I have a 7month old son now. He was exposed to ultrasound since 3 months of pregnancy. Ultrasound has been our medium of checking improvements our son’s health. Now he has grown healthy without any possible brain damage. Anyway just sharing, Thanks for the great discussions on the comment area. Had fun reading and have been informed with all your thoughts.

  35. nybgrus says:

    @Dr. Hall: I feel honored to be able to pick your nits. And I really mean that geniunely. Thank you.

    @nmarasigan: I think I speak for everyone here, particularly the authors, when I say thank you for the kind words. I view this blog as a great way to share critical thinking and good understanding of the (medical) world around us. I hope the authors agree.

    @d2u: Bleepin’ awesome summary. I love having a non-squishy scientist around to bestow upon us some knowledge (I refer to myself as a squishy scientist :-P). The spread of knowledge and ideas like this is just… awesome.

    @michele: I’ve said it before and I will say it again: I love that “artsy” types like yourself exist. You prove that science is more than taped-up thick frame black glasses and Star Trek mixed with esoteric science (not that there is anything wrong with that). You show how wonderful the marriage of artistic creativity, critical thinking, and an appreciation of science can be.

  36. rmgw says:

    Crumbs! Spot the odd one out! she is a ” homeopath, a craniosacral practitioner, a vegan, and a yoga teacher.”

    Now which one is an ethical position which has nothing to do with quack medicines or techniques of any kind? (Answer – vegan!). Let’s get our terminology right, please!

    Even the Bill Clinton sort of diet-only veganism has the support of the American Dietetic Association on nutritional grounds – it’s not even a strange dietary choice!

  37. nybgrus – Thanks, although I’m pretty sure I’m not all that. I do appreciate the tolerance all the folks here show for my lack of science skills and tendency to tangent.

    I actually don’t believe in the whole nerdy vs artsy dichotomy. I know too many artists who are nerdy or fascinated with some technique to the point of nerdiness and too many scientist, engineers, etc who are very creative.

    I think the dichotomy is curiousness vs in-curiousness. I am thankful to you and the other curious minds here at SBM who allow me to learn so many fascinating things.

  38. icewings27 says:

    @Amy (T) –
    I know that some states have stricter abortion laws, but in general, if you live in the US, you can get an abortion up to “viability” which is generally considered between 22-24 weeks gestation.

    It is nonsensical for a state to make abortion illegal on the basis of the fetus’ sex, if abortion is already legal up to viability. Obviously, if a woman wanted an abortion after 22-24 weeks, then the sex of the fetus would not be a valid reason.

    But in general, if you are under 22-24 weeks pregnant you can get an abortion in the US (with the exception of some states that restrict abortion further) for any reason at all.

    For example, let’s say I get an ultrasound at 16 weeks and find out that I’m carrying a boy, and that he has a serious heart defect, and that he has a cleft palate. The following week, I get an abortion. It doesn’t matter why I got the abortion – it could be for one of the three reasons I listed, or for something else unrelated. It’s a legal abortion.

    Back on topic, a bit here…Ultrasound can discover defects that may lead a woman to abort, but that in itself is not a reason to limit ultrasounds, given that abortion is legal in the US up to viability regardless of what route the woman took to make that decision. I hope that clarifies my point.

  39. Harriet Hall says:


    I hope you didn’t think I meant that veganism had anything to do with quack medicine. I didn’t say that. I think it falls more in the same category as her recommendations that pregnant patients eat only organic food. Not quackery, but more based on ideology than on clear science.

    Veganism is not always an ethical stance: it can be adopted for health reasons, as in Bill Clinton’s case. And its benefits are frequently hyped beyond the known facts. The ADA does indeed say a vegan diet can be healthful, but it doesn’t exactly recommend it. I wrote about Bill Clinton’s diet and concluded it was “based more on hope and desperation than on solid scientific evidence.”

  40. Amy (T) says:

    Icewings27, sorry that was so late, my comments spent a day in moderation! Yes, I agree with your point it’s nonsensical, I was just pointing out some states have officially outlawed abortions based on sex, even if that means nothing in reality.

  41. Jan Willem Nienhuys says:


    Ultrasound technology is based upon ultra high-frequency sound waves, which bombard the child in the womb at an extremely high rate of speed.

    The lady seems to think that the quicker the vibration, the more deleterious.
    Now the kind of sound that shatters glass is a few hundred hertz (high C is 1055).

    If it was the frequency that counted, then ordinary sunlight would be absolutely lethal, having a frequency of 500,000,000,000,000 Hz, which is about 200,000 times the frequency of a microwave oven (and about 10,000,000,000,000 the frequency of electric current that can kill you). Shocking, isn’t it, that people dare to go out in the sun. And don’t think that you don’t absorb sunlight: a little into the infrared we all are as black as snow.

    It is almost endearing to see a person talking about ‘waves with a high rate of speed’. The velocity of sound waves hardly depends on the frequency.

    When you see or hear ‘rate of speed’, you know you are dealing with a person without knowledge of science, see

    It’s just the cargo cult science as popularized by Feynman

    Instead of rather fictional primitives using coconuts for earphones, who enact the landing of the cargo planes, we have 100% tangible Westerners pretending to do science and use sciency words but overwhelmingly wrong about all details.

  42. Okay, I had to check out termination based on cleft lip and palate (or other non-serious conditions) further. I do agree with above poster who says that for the period of time that abortion is legal, regardless of reasoning, that the woman’s motivation is not really relevant.

    After a lot of googling, though (had to get past all the U.K. abortion laws, which I’m just not going to get into, not being British.) That I could see as a concern from ultra-sound is doctor error and doctor presentation when a potential malformation is seen in an ultra-sound.

    I believe that doctor error would be covered in HH’s article under false alarms.

    As for doctor presentation, In my search through groups for parents with cleft I did find that a small number of women reported that their doctor recommended terminating a fetus based on ultrasound that indicated cleft lip and palate alone. Other mom’s reported that their doctor’s informed them that it was an option, but did not recommend it. Other did not bring up termination at all.

    Here is one thread as reference

    I found other discussions as well, but they are in a private group.

    Perhaps this speaks to a need for updated doctor education or perhaps it is an example of a few bad doctors using technology the to execute a twisted social agenda. Hard to say based on online discussion.

  43. If someone presented data showing that 3 death penalties occurred per year, 2002-2008, in which DNA data showed the the person was falsely put to death, that would be enough to raise an eyebrow.

    July 5, 2011: London, England: “Data released by Britain’s Department of Health showed that from 2002 through 2010, almost 18,000 abortions were performed in the country due to substantial risks to the baby being seriously handicapped or deformed. Of this number, 26 were fetuses with cleft lips and cleft palate problems.”

    I agree that if you do not think the fetus is an actual human, this is no big deal, and reason does not really matter. However, I believe the fetus is an actual human, so to me it is a human rights tragedy, and all of us “progressive,” educated people ought to be opposed to abortion, and also continue to be in support of services for those with disabilities, etc.

  44. medvstherapy – I see that you have an opinion on abortion. Did you notice that the article and thread were generally a look at the possibility of risks from ultrasound?

  45. MicheleInMichigan: should “abortion” be in “Reasons for doing unltrasound” section, in the post, or in the “Reasons for not doing ultrasound” section, in the post? Sex-selection abortion and other aspects are introduced there.

    If you can label me as crazy or dumb, then you can ignore the facts I have posted. I put your note above in the “try to define this person as dumb” category.

    Ultrasounds are being used to determine whether a fetus has cleft palate, so that the fetus can be aborted. If that is OK with you, then that is OK with you. I believe it fits the definition of “eugenics,” which, for me, is not OK. I understand that reasonable, intelligent people can disagree on this.

  46. JJ from Cowtown says:

    MedsVsTherapy: “However, I believe the fetus is an actual human, so to me it is a human rights tragedy”

    So you’re outraged by more than the 1% of 1% of abortions that your article talks about.

    And you’re playing the victim/martyr card before anyone’s even disagreed with a word you’ve said.

    Fantastic. Here’s hoping everyone realizes you’re just here to pick a fight.

  47. Amy (T) says:

    Medsvstherapy, you said fetus=human, so when it’s an embryo (under 10 wks), is that different?

    As for worrying about US for abortion, we don’t know what the parents will choose. Some would never have an abortion, they just want to be prepared if something’s wrong, have specialists doctors ready. Some things found wrong on an US can save a child, interventions can help a child that may have never made it to term live, or have been disabled not be at all.

  48. medvstherapy, I was not attempting to call you dumb only seeking clarification on how your views on abortion relate to the topic of the article.

    As I said before, I believe that many parents find it useful to find out that their child has a cleft before the birth so that they can prepare for the care the child will need, find a hospital with a cleft team, feeding specialist, etc. Belonging to a number of groups for parents of children with cleft and other disabilities, I have heard many parents express appreciation for that prep time and I also believe it is advantageous to the child, since they have a parent that has had some time to learn to advocate for them.

    As the adoptive parent of a child with clcp, we did not have an ultrasound, but we did have a diagnoses before we brought our son home and I found this tremendously useful in finding our doctors, preparing for his diet, handling questions from friends and family, etc.

    There are other congenital conditions, such as congenital heart disease, where having advanced warning of the condition may mean a better chance of survival for the baby.

    If you feel the need to call me an eugenist because I believe that judicious use of ultrasounds to diagnose congenital malformations is a good thing, I’m confused. I would generally say that a eugenist is someone who advocates for the elimination of people with traits they consider inferior. I have not advocated for the elimination of any people or (fetuses for that matter). I do not believe that an ultrasound that shows a diagnoses of a malformation or the sex of a child is advocating for the termination of a pregnancy.

    But, we could go back and forth. I haven’t seen any new info that suggest a change of views is called for on my part, so time for me to bow out of this particular discussion.

  49. Amy asked:
    “Medsvstherapy, you said fetus=human, so when it’s an embryo (under 10 wks), is that different?”
    I answer: yes, my belief is that it is a human.

    An embryo is far differnt from a seed or a virus. I think the prevailing view now is that a seed is alive even when dormant for years, and that there is not really a prevailing view or consensus on whether a virus is ever “alive.”

    I believe people should strive to be like MicheleInMichigan and conceptualize a person with cleft palate as a totally lovable, acceptable human worthy of even being adopted.

    I know people believe an embryo or fetus is not yet a human, developmentally. That is what I used to think, before I spent any time thinking abt it, and ignoring things like ultrasounds being used to determine whether a pregnancy should be ended, along with the various other purposes an ultrasound can serve.

    I think the discussion of the good and bad of ultrasound brings up ethical questions, like many medical advances bring up.

    Cowtown sez: “So you’re outraged by more than the 1% of 1% of abortions that your article talks about.”

    I can’t exactly figure out what this refers to, but I don’t think it is a defense of any human rights violation to say that it only afefcts a tiny number of people. If there are only two children captured into sex trafficking per year, that is two too many for me. If there are two wrong deaths-by-death-penalty per year, that is two too many for me.

    If two eight-week-old embryos get terminated because cleft palate was detected, that is two too many per year for me. I understand other people do not think an eight week old embryo is a human, so I can see how other people don’t see any tragedy.

  50. medvstherapy – Perhaps you’d be glad to hear that personal experience tells me the vast majority of people do understand that a child with a cleft is as human, lovable and worthy as any other child. Of course, there are probably people who I haven’t meet who have to “strive” for that view or have other odd or unhealthy views. I don’t think it would be healthy for a child with a cleft to have them as parents.

    I don’t understand what “worthy of even being adopted” means. Perhaps you could take a break and read up on adoption language, ideas and the practicalities before commenting in a way that is kinda insulting to those of us in the adoption community.

    Also, I don’t conceptualize my son as a human or lovable. He IS human and lovable. If you had a car accident and suffered an injury to your face that required a few surgeries would you be happy and content when your husband or wife told you they “still conceptualize you as human and lovable”?


    Your “caring” for those with congenital malformations or disabilities is reading like a charade to support your general anti-choice views. I hope it is only that you lack the appropriate language…

  51. Amy (T) says:

    micheleinmichigan, I completely agree with you (as usual). I found medvstherapy’s wording to be a bit offensive as well. every child born should be loved and cared for. “worthy of being adopted” just sounds sick, I’m not sure what you meant by that either. even very pro-choicers feel when a child is born, it deserves unconditional love (adoptive or biological). if something happens in childbirth that leaves a child disabled for life, it’s not like every pro-choicer would throw up their hands and not want the child, any loving parent would do all they can to care for the child and give it the best possible life. the impression I’m getting from medvstherapy’s posts are that because one would terminate a 20 wk old fetus, we therefore don’t care about children once they are born. I feel most people do the US because they care about the future of their fetus (as an aside, if you read my first post, I wrote how my friend lost her premature 1-month old baby, which possibly would have had a very different outcome with a 2nd US).

  52. Josie says:

    no comment on the abortion side of this discussion…

    I was surprised to see that heat generation in mice was a (faux) concern!

    Granted I have just an anecdotal comment to offer but it’s an anecdote from have screened lots of mice with high frequency ultrasound (up to 55MHz).

    When I gel my mice up and get them under a transducer I have them on a heated platform. If anything the little buggers suffer hypothermia without an external heat source (they are knocked out too so of course that doesn’t help their homeostasis).

    I think I am going to look into this before some animal rights activist accuses me of cooking my living mice.

    Of course I am just a brain damaged lefty, so I really can’t be held accountable.

  53. Elwood says:

    In Australia, most pregnant women will have a first-trimester dating scan (to confirm pregnancy and dates) and a second trimester anomaly scan (at about 20 weeks) to check fetal development. A high number is are also having a FTS scan at 12-14 weeks (First Trimester Screening for trisomy, especially Down’s).

    Despite negligible evidence for definite bio-effects at the energy levels used in diagnostic imaging the ultrasound profession’s guideline is to expose the fetus to ultrasound according to the ALARA (As Low As Reasonably Achievable) principle. That is, scanning for purely non-diagnostic reasons is not recommended.

    Non-diagnostic/entertainment ultrasounds are available, usually at some expense, and usually only if diagnostic scans have already been performed. (The operator of these businesses are usually sonographers wanting to be in the entertainment/baby-bonding business, not the counselling busineess.)

    There’s a bit of a DA/DT attitude to these
    types of companies
    – on the one hand, it’s over-use of an (probably safe) modality, with ultrasound exposure for no diagnostic benefit – although judging by the testimonials the parents do benefit – and on the other hand it’s professionals using their skills to make money, and their own associations are not very strong in condemning them.

    Also, I think it’s been shown that diagnostic imaging when used in the right conditions (focussed at one point for prolonged periods) can raise local temperature by about 1 degree C. One, not thousands. In practice, this does not happen.

  54. Calli Arcale says:

    Any historical comparisons of left-handedness rates must take into account that left-handedness was stigmatized and it used to be customary to discourage left-handedness by forcing children to use their right hands.

    Very much so. I saw red at that part of the OP and found it difficult to focus on anything else. My husband is left-handed, and his grandmother briefly attempted to “correct” this before his mother figured out what she was doing and put a stop to it. (His mother is also a leftie, but had a mother who didn’t care about things like “kids are supposed to be x so make ‘em” and consequently never got guff for her handedness.) My mother is also left-handed. Her grandmother wrote with her right-hand, but painfully slowly — she had been born left-handed (obviously without a single ultrasound) and had endured repeated raps on the knuckles from her schoolteacher’s ruler and having her left hand tied behind her back until she finally gave up and learned to do things with her right hand. It’s a horrible thing to do to someone, really, and to hear someone in the 21st Century espouse a view that left-handedness is somehow evidence of brain damage is frankly infuriating. I’m glad the lefties who have posted so far have shown such admirable grace and wit in response.

    I’m sure she just pulled her links out of thin air, but it is probably true that ultrasound is linked to “Early labor, premature birth, miscarriage, low birth weight, poorer health at birth, and perinatal death.” This is because you’re much more likely to get an ultrasound at the tail end of your pregnancy if things are going badly — multiples, pre-eclampsia, preterm labor (yes, preterm labor can cause ultrasounds!), lack of fetal movement, bleeding, placenta previa, etc. And ultrasound improves the odds of a positive outcome in those cases. I have some words to describe this lady who calls herself a doctor and opines on the risks of ultrasound, but they aren’t printable.

  55. Calli Arcale says:

    BTW, as far as screening for birth defects, I’m a huge proponent of early intervention. The sooner a parent knows about them, the sooner something can be arranged to deal with them. And, honestly, if the child has a fatal birth defect, there really isn’t much point continuing the pregnancy. Most are not detectable on ultrasound until quite late in the pregnancy, but these would be things like anencephaly and a failure to develop the proper internal organs. Yes, it is sometimes possible to save a child born without kidneys, but it’s excruciatingly expensive and will usually result in a great deal of misery for the child even if the child is lucky enough to live long enough to qualify for a transplant and then actually get one, and I could understand parents opting for a quicker, and perhaps kinder route in such a situation. I don’t know what I’d personally do, and I honestly hope to never find out.

  56. Tracy W says:

    Sorry about the late comment, but I’m pregnant and am reading up on obstetrics while trying to decide my birthplan and came across this.
    It always strikes me that pregnant women are advised to minimise risks in so many ways, with the exception of going near the roads. Does anyone who adopts the As Low As Reasonably Achievable principle advise women to stay as close to home as possible during their pregnancies as much as possible to avoid the risk of being run over by a car? (Wording “as close as home” to cover the case of the benefits of some mild exercise, going to my local park provides space for walking, and indeed running, while minimising the risk of being run over by a car along the way, but I wander further afield than that). It was a wonderful feeling both times I saw the fetus on ultrasound, that counts for a lot.

    Elwood: and on the other hand it’s professionals using their skills to make money, and their own associations are not very strong in condemning them

    Why should their own associations be condemning them at all? I haven’t got a non-diagnostic ultrasound, because I don’t think that the pleasure to me and my loved ones is sufficient to offset the price, but I know many other people have, and many of them are very happy with the results. So providing non-diagnostic ultrasounds increases consumer surplus (as judged by the consumer), and as any dangerous side-effects appear to be very very small, and assuming that the professionals are not misadvertising what they can provide, I don’t see why any professional association should object to professionals using their skills to make themselves and their customers better off. I’m not calling for active support of it, I think the market will do that well enough, but condemning it, however weakly, seems ridiculous. Does anyone think that actors’ unions should condemn actors who engage in live theatre as said actors are professionals using their skills to make money and as they encourage people to travel to the theatre, exposing them to the risk of being hit by a car?

  57. nybgrus says:


    In Australia healthcare is paid for by the government. Thus, standards of practice are set by government policy following the evidence base. So they don’t condemn only for dangers associated, but also for lack of utility and costs incurred. If people want to pay completely out of pocket for an extra scan, they can and they do. But in many cases it is easy enough to still end up billing the government for at least part of the cost and thus the professional body must condemn the usage just on that principle alone.

    Hope that clears things up a bit.

    (and yes, US are very safe and you can have as many as you want if you can foot the bill).

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