Natural Childbirth IIb: Ultrasound Not as Safe as Commonly Thought | Chris Kresser

Natural Childbirth IIb: Ultrasound Not as Safe as Commonly Thought

by Chris Kresser

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In the last article in this series on natural childbirth, I reviewed evidence suggesting that routine prenatal ultrasound does not improve birth outcomes for mothers or babies, and that organizations like the American College of Obstetricians & Gynecologists recommend ultrasound scans only for specific reasons.

In this article I’m going to review evidence on the safety of routine ultrasound and Doppler scanning, and make recommendations based on that research.

The potential adverse effects of ultrasound

According to Australian family physician Dr. Sarah Buckley, MD in her book Gentle Birth, Gentle Mothering, ultrasound adversely affects body tissues in three primary ways:

  • Heat
  • Cavitation
  • Acoustic streaming


The sonar beam can cause heating in the tissues beings scanned. During normal pregnancy, increases in whole-body temperature of up to 4.5 degrees F (2.5 C) are presumed to be safe, and research suggests that elevations of tissue temperature up to 1.8 – 2.7 degrees F (1.0 to 1.5 C) caused by ultrasound are also safe.

The degree to which ultrasound machines raise temperatures in the tissues depend on which tissues are scanned. Bone heats more than soft tissue, which in turn heats more than fluid. Heating is also dependent upon exposure time, the intensity of the machine, and whether the transducer is held stationary or moved frequently.

Doppler ultrasound, which uses continuous rather than pulsed waves, has been shown to cause significant heating – especially in the baby’s developing brain. A recent study suggests that heating in late-pregnancy fetal tissues exposed to normal pulsed and continuous Doppler ultrasound may be higher than what is regarded as safe: 2.5 to 10.4 degrees F (1.4 – 5.8 C) respectively.

A 1997 study found that significant temperature increases can occur at or near to bone in the fetus starting in the second trimester, if the beam is held stationary for more than 30 seconds in some pulsed Doppler applications. This in turn can lead to heating of sensory organs incased in bone.

Though both animal and human studies have shown that temperature elevations can cause abnormal development and birth defects, so far human studies have not shown a direct causal relationship between diagnostic ultrasound exposure during pregnancy and adverse effects to the developing baby.

However, it must be pointed out that all human epidemiological studies were conducted with commercially available devices predating 1992, with acoustic outputs not exceeding an intensity of 94 mW/cm2.

Current limits in the U.S. have risen dramatically, and now allow intensities of up to 720 mW/cm2 – more than 7 times the limit in 1992. This means we have no large, population-based studies examining the effects of ultrasound at the much higher intensities commonly used today.

This is highly problematic, because, according to a 2001 review called “Guidelines and Recommendations for Safe Use of Doppler Ultrasound in Perinatal Applications“:

When modern sophisticated equipment is used at maximum operating settings for Doppler examinations, the acoustic outputs are sufficient to produce obvious biological effects, e.g. significant temperature increase in tissue or visible motion of particles due to radiation pressure streaming effects. The risk of inducing thermal effects is greater in the second and third trimesters, when fetal bone is intercepted by the ultrasound beam and significant temperature increase can occur in the fetal brain.

A 2007 study reached a similar conclusion:

(1) thermal rather than nonthermal mechanisms are more likely to induce adverse effects in utero, and (2) while the probability of an adverse thermal event is usually small, under some conditions it can be disturbingly high.


Cavitation occurs in tissues with significant pockets of gas (such as the lung and the intestine) after birth. There is no consensus on the significance of cavitation effects in human fetal tissue, but some evidence suggests that mammalian tissue may contain microbubbles that are susceptible to cavitation effects.

Acoustic streaming

Acoustic streaming involves a jet of fluid created by the ultrasound wave, which causes a mechanical shearing force at the cell surface. While the effect of this force is not fully understood, research suggests that it may change cell permeability and have adverse effects on both early and late prenatal and postnatal development.

Animal studies suggest diagnostic levels of ultrasound may cause harm

One study found brain hemorrhages in mouse pups exposed in the womb to pulsed ultrasound at doses similar to those used on human babies.

Another study found exposing adult mice to dosages typical of obstetric ultrasound caused a 22 percent reduction in rate of cell division and a doubling of the rate of apoptosis of cells in small intestine.

Other research has found that ultrasound induces bleeding in the lungs among other mammals, including newborns and young animals.

The American Institute of Ultrasound in Medicine concluded:

There exists abundant peer-reviewed published scientific research that clearly and convincingly documents that ultrasound at commercial diagnostic levels can produce lung damage and focal haemorrhage in a variety of mammalian species…. The degree to which this is a clinically significant problem in humans is not known.

I want to be clear: we can’t extrapolate the results of these animal studies to humans, and so far, many longer-term human studies have not shown harm to the fetus from diagnostic ultrasound exposure. However, when the stakes are this high (i.e. the health of our children), I believe the animal study results warrant caution and further study before plowing ahead with ultrasound technology.

Some human studies also suggest harm…

Single or small studies on humans exposed to ultrasound have shown that possible adverse effects include premature ovulation, preterm labor or miscarriage, low birth weight, poorer condition at birth, perinatal death, dyslexia, delayed speech development, and less right-handedness.1

This is especially true for Doppler ultrasound, which is used in specialized scans, fetal monitors and handheld fetal stethoscopes (sonicaids). Ordinary scans use pulses of ultrasound that last only a fraction of a second. The machine uses the interval between pulses to interpret the echo returns. Doppler, on the other hand, uses continuous waves – leading to much higher levels of exposure than with pulsed ultrasound.

A large UK study found that healthy mothers and babies that received two or more Doppler scans to check the placenta had more than 2 times the risk of perinatal death compared to babies unexposed to Doppler.

An Australian study found babies that received more than 5 Dopplers were 30% more likely than babies that received routine (pulsed) ultrasound to develop intrauterine growth retardation (IUGR). This is ironic because Doppler is often used specifically to detect IUGR.

A randomized clinical trial published in 1996 split 2,743 women into two groups: one that received a single doppler at 18 weeks and further scans only when clinically indicated, and another that received 5 Doppler readings during pregnancy. When compared with the regular group, and after adjusting for other confounding variables, babies in the intensive group tended to be shorter when measured at birth and at 2-3  days of age. There were also reductions in the circumferences of the chest, abdomen and mid-arm, and in the skin-fold thicknesses of the triceps, parascapular and subscapular regions – although these differences weren’t statistically significant.

A later study in Lancet found a similar effect on fetal growth in women receiving repeated ultrasound exams, although measures of growth and development later in childhood (up to age eight) were similar in both groups.

A case control study of 72 children who had undergone a formal language evaluation found that children with delayed speech had a higher rate of ultrasound exposure in utero than normal controls. Their findings suggested that a child with delayed speech was twice as likely to have been exposed to prenatal ultrasound. (Note that this is a correlation and doesn’t prove causation.)

…while other studies suggest ultrasound is safe

On the other hand, a recent World Health Organization (WHO) review of the literature in 2009 concluded that “exposure to diagnostic ultrasonography appears to be safe.”

However, even in this review they did express some concern about the association between left-handedness in males and exposure to Doppler ultrasound. Non-righthandedness is sometimes a marker of damage or disruption to the developing brain. 2

Another review in 2008 concluded:

At this time, there is no specific reason to suspect that there is any significant health risk to the fetus or mother from exposure to diagnostic ultrasound in obstetrics. This assurance of safety supports the prudent use of diagnostic ultrasound in obstetrics by trained professionals for any medically indicated examination.

What are we to make of these conflicting results?

One of the reasons it’s difficult to make any clear determinations from the research is that the methodology of many of the trials is faulty. For example, in a randomized controlled trial in Sweden in the late 70s that found no differences in hearing, vision, growth or learning at age 9 in kids exposed and unexposed to ultrasound, 35% of the supposedly unexposed group actually had a scan. This means there was no true control group.

In fact, there are very few studies at all comparing outcomes between women who have received no ultrasounds at all and women who have received ultrasound during pregnancy. This is the kind of research we need to make an accurate determination of the effects of ultrasound on mothers and developing babies.

Another problem which I mentioned earlier in the article that casts doubt on current safety assessments is that scanning intensities used today are up to 6-8 times higher than they were in the 1990s, when all of the large population-based studies assessing ultrasound safety were done. This means we have no data on the large population level indicating whether ultrasound scanning at the frequency and intensity commonly practiced today is safe.

In a 2002 review of the safety of ultrasound in the prestigious journal Epidemiology, the authors concluded:

Until long-term effects can be evaluated across generations, caution should be exercised when using this modality during pregnancy.

Weighing the risks and benefits of routine ultrasound

The evidence I’ve reviewed here does not prove that a single ultrasound scan at relatively low intensity performed by a skilled operator will cause harm to a developing baby.

However, there is sufficient evidence that multiple pulsed ultrasound scans, or as few as two continuous wave Doppler scans, or any ultrasound scan performed by an unskilled operator may cause harm. There is also a pressing need for large epidemiological studies to be performed using the higher ultrasound intensities commonly used today.

When making a decision to perform any medical diagnostic test or procedure, benefits must always be weighed against risks. It’s rarely a black or white issue. Clearly, if ultrasound was 100% safe with no potential for harm, there would be little medical reason not to perform routine ultrasound during pregnancy.

But the evidence indicates that ultrasound is not risk-free, so we are forced to weigh whatever benefits routine ultrasound might provide against the potential harm it could cause. That harm could be physiological – including the effects we’ve covered in this article – and it could also be psychological. And of course psychological effects like stress and anxiety very quickly produce real physiological changes in both the mother and the baby.

The authors of the 2010 Cochrane review on ultrasound remind us that:

Subjecting a large group of low-risk patients to a screening test with a relatively high false positive rate is likely to cause anxiety and lead to inappropriate intervention and subsequent risk of iatrogenic morbidity and mortality.

Translation: giving all women ultrasounds may end up introducing unnecessary stress and anxiety, which in turn can produce real complications that would not have otherwise occurred. The screening for potential abnormalities can become a self-fulfilling prophecy.

Routine ultrasound also increases the likelihood that more tests will be performed, which could also increase the risk of complications. In a trial of Doppler in 4,187 low-risk pregnancies in France, the only significant result of using doppler was an increase in the number of ultrasound and doppler examinations subsequently conducted. There were no other effects on the management of pregnancy.

And then there is the new trend of non-medical fetal ultrasound (also known as ‘keepsake’ ultrasound), which is defined as using ultrasound to view, take a picture, or determine the sex of a fetus without a medical indication. This practice involves long exposures using 3-D and 4-D ultrasound techniques, which have not been studied adequately, and do not provide the patient with medically appropriate data.

For this reason, major organizations like the American College of Obstetricians and Gynecologists, AIUM and the FDA do not support keepsake ultrasound.

Recommendations and personal experience

Based on the evidence we’ve reviewed in this article, I recommend minimizing exposure to ultrasound during pregnancy in the following three ways:

  1. Using ultrasound only when medically indicated, i.e. only when a problem is suspected, rather than as a routine screening to determine the sex of the baby or check on its development.
  2. Minimize total exposure time (by choosing a skilled and knowledgeable operator).
  3. Minimize exposure intensity (i.e. avoiding Doppler during the first trimester especially).

Steps 2 and 3 are especially important in light of the lax regulation of ultrasound and the incredibly high variability of skill of ultrasound operators. In the USA, UK & Australia, ultrasonography training is voluntary – even for obstetricians – and the skill and experience of operators varies tremendously. Most operators don’t follow the scientific literature and aren’t aware of the safety issues involved with repeated and high intensity exposure.

In cases where abnormalities are suspected, a woman may wish to have an ultrasound to determine whether an early termination is warranted. The moral, ethical, economic and social issues involved in that decision are far beyond the scope of this article, and cannot be answered through research alone.

I support the right of a woman and her partner to choose what is best for them in this regard; after all, it is they who have to live with the results of their decision.

My wife Elanne and I chose not to have any ultrasound scanning done during her pregnancy, even though she was 39 when she conceived and thus at higher risk for certain genetic abnormalities.

We discussed it at length. In the end, we decided that what we might lose in getting the scans was greater than what we might gain. We felt the stress that a minor or uncertain problem on the scan could produce, and the worry and concern we’d feel waiting for the next scan, and the next one… would interfere with our relationship with our growing baby.

We also decided that we would carry the pregnancy through to full term, regardless of whether an early scan (had we had one) turned up a risk for an abnormality. It took us 2 years of off-and-on attempts to get pregnant, and because of the relatively high risk of false positives and the uncertain results of those genetic tests, we were willing to live without the information a scan might have given us. If it hadn’t taken us so long to get pregnant, or if Elanne had been younger when she did get pregnant, perhaps we would have made a different decision. Perhaps not.

I’m in no way suggesting this is the right choice for everyone. I strongly recommend that you educate yourselves about the risks and benefits of ultrasound first, and then consider your own personality, circumstances and values before making a decision. No one – not me, your doctor, or any other authority – can make this choice for you.

Articles in this series:

  1. Buckley S. Gentle Birth, Gentle Mothering. Celestial Arts, 2009. pp. 88
  2. Odent M. Where does handedness come from? Handedness from a primal health research perspective. Primal Health Research 1998;6(1):1-6.)


Join the conversation

  1. Thank you for this very detailed and well documented explanation!

    I read the full explanation after my wife did an ultrasound scan at 11 weeks (she had spotting and she was worried), without knowing that there is the NT scan scheduled at 12-13 weeks. Our GP said there was no scan planned at 12-13 weeks. How could she be so wrong ? (plus this GP is a mom herself). This caused my wife to be very upset about all this, and it ended in tears. Our intuition told us from the beginning that we want to minimize ultrasound scans. Your very good explanation confirmed this.

    This experience taught me (once again) that the doctor cannot be blindly trusted, and that the patient should do some research on his own.

    Some further research told me that an NIPT scan, for women >35, would be a better choice than the typical FTS scan. My wife falls into this at-risk category, so we will skip the NT scan and go ahead with the NIPT scan for which we will have the result at week 13.

    The NT scan can only ASSESS risks, it is not a diagnostic. And the NIPT test gives more accurate results for women >35.

    This said, you should obviously contact your obstetrician if you have concerns.

  2. I do often wonder about those that propose a more natural approach to health and their thoughts on abortion. It wasn’t entirely clear here. I would hope though that with such a scientific foundation and respect for human life that they would reject abortion. Human life clearly starts at the moment of fertilization (once it occurs, there is a completely unique human being growing rapidly) and “termination” has to forcibly end the life of the new child that is the most vulnerable human being. We need to protect human beings in every stage, not “terminate” (re: euthanasia/abortion) when they are inconvenient, sick, the timing is not good etc.

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  4. I have read the article, thank you. I found this article after feeling concerned yesterday at a scan at Kings College Hospital fetal research center in London which I might add has some of the leading researchers in the world for fetal medicine. I was concerned when the doctor mentioned two more scans at 32 and 36 weeks to be added which were not offered in my previous pregnancies, the last one being in 2012. I note that the doctor informed me that they were to monitor growth and to check if the baby had turned and it’s head was down and engaged. Now, the midwives seemed to have no problem monitoring growth from traditional non invasive methods in my three previous pregnancies, so I found alarm bells ringing. I actually read an article on this subject around ten years ago and because my first pregnancy was with twins and I did have extra scans because of this, it interested me. I note that the extra scans have only recently been introduced, to my knowledge in the UK. I already find it extremely disturbing that routine vaccines in pregnancy were introduced in the UK in 2013 which I have researched quite deeply after nearly losing one of my twins after an adverse reaction 11 years ago; which leads me to wonder if these extra scans in later pregnancy have actually been introduced to monitor whether the administration of vaccines shortly before these scans interfere with fetal growth and defects. I am not stating this as fact, just speculation in my own mind, but thought it’s worth mentioning as it’s something to think about. The thing is, what mother would sign up to a study to check whether vaccines in pregnancy affect fetal growth, so it seems to me that this is the only way to check and my inner conscious and intuition tells me that there is a deception or something amiss going on here.

  5. This paragraph is a direct quote from Sarah Buckley and should be cited as such:
    “This is especially true for Doppler ultrasound, which is used in specialized scans, fetal monitors and handheld fetal stethoscopes (sonicaids). Ordinary scans use pulses of ultrasound that last only a fraction of a second. The machine uses the interval between pulses to interpret the echo returns. Doppler, on the other hand, uses continuous waves – leading to much higher levels of exposure than with pulsed ultrasound.”

  6. I’m concerned because my OB wants me to do the non-stress test 2 times per week starting at 36 weeks. If NSTs are done with a doppler that’s 30 minutes of constant exposure… I understand they want to make sure my placenta is functioning well (due to “advanced maternal age” they’ve labeled me as having a “geriatric pregnancy”), but I do not feel good about this amount of doppler expose. My baby is active (I’m 35 weeks now) and feels fine!

  7. I found a good link with graphs that help you visualize the intensity and frequency of pulsed versus Doppler ultrasound. It seems that Doppler fetal heart monitors aren’t much cause for concern since their intensities are low -even if the frequency of Doppler heart rate monitors are high. The intensity on a typical heart rate monitor isn’t enough to cause heating of tissues. But what really is a concern is the Spectral Doppler with waves that are both frequent and intense which produce images for a screen. The Spectral Doppler scan is often used to check the flow of blood via the placenta into the baby’s major arteries. This is the type of ultrasound that has caused retarded growth in fetuses in the studies cited. That particular article seems to recommend keeping pulsed scans under 30 minutes and Spectral Doppler scans under a minute. But who knows if the intensities of the scans measured are the same used in machines today – so I’d personally halve those recommendations. Anyway, after having a missed miscarriage, I think it’s good to know whether the baby is still alive at 12 weeks. Otherwise it could die and cause pelvic infection and sepsis, hurting the mother’s chances of having another baby. I would opt for a quick monitoring of a heartbeat during that time. I’d also do a quick pulsed ultrasound which checks for placenta previa and spina bifida and pair it with a blood test to check for chromosomal abnormalities. Here is the link with the ultrasound graphs:

  8. Hi, I did not have ultrasound with my first baby and now I’m pregnant with my second. I don’t know how far along I am because my cycle has been anywhere from 25 to 70 days for the last year and a half, plus i think i might have forgot to record my last period. I started a cycle on July 8, but can’t remember if i had one in August (I know it’s terrible I can’t remember this). I know I did not have one in Sept or Oct., therefore I could be due anytime between the end of April and beginning of July which is a big range. My midwife would prefer that i do an ultrasound to get a better due date. If i got a 2d and ask that it’s under one minute, would that probably be ok, or should i maybe not get one? Is there a way to go about finding a technician that uses older equipment with the lower frequency?

    • Reevaluate the risks by discussing with professionals, the recently discovered human studies. Those indicate extreme risk. Improper focus on due date can bring unnecessary worries and false diagnostics. In 1984 the NIH refused to endorse routine ultrasound, for many reasons which have still not been refuted. Since then, the FDA-allowed machine intensities have risen 8-fold! Increase your knowledge of your body’s ability to birth a child, and increase your environmental knowledge. See

  9. So do pulse instead of doppler and keep level and time low. Don’t sit there and stare and have unnecessary pictures taken. Don’t get an excessive amount unless it is absolutely necessary. We had a doctor recommend 9. That was a little crazy. We stopped at 2. I guess every case is different. Sometimes we make a deal with the devil with medical tests in general. We find some information we are looking for but have to pay later, sometimes with something much worse.

    • It is difficult with modern machines to use ultrasound at low intensity. Most operators are deficient in skills according to several polls.

      Reevaluate risk: Human exposure studies are presented in my unprecedented bibliography, studies that examined 2,700 women, their abortive matter after ultrasound exposure.. See

    • There exists abundant peer-reviewed published scientific research that clearly and convincingly documents that ultrasound at commercial diagnostic levels can produce lung damage and focal haemorrhage in a variety of mammalian species…. The degree to which this is a clinically significant problem in humans is not known.

  10. Well to put it politely this is rubbish. As a trainee Sonographer, who is currently back at university to complete the required course that all Sonographers have to in order to practice in the UK, you have a done a very good job at manipulating fact. There is very little known facts about safety of ultrasound in humans because it is classed as unethical to conduct the same research in humans as we do in animals. Animals that have shown adverse effects have had ultrasound applied for long periods of time, at high frequency, in one area … something that would not be done in real life, these are extreme exposures. Doppler dose use higher frequencies and should be kept to a minimal (which it is) and is not used in the 1st trimester due to the rapid fetal development. There are no legal laws at exposure as it is such a complex system that is individual to the patient, but there are guidelines which me and the Sonographers work to. Technology has improved vastly, but every time an exam is selected it starts with the lowest acoustic power possible and the improvement in technology has allowed for the use of image manipulation first before increasing power. I have never increased power – which in THEORY is believed to cause thermal effects – nor have I seen anyone else do so. It pains me that I can not write a better response as I am currently writing an assignment, hence why I stumbled across your blog (I will not call it article). I just hope that no one bases their refusal of an ultrasound on this bias manipulation of facts. To everyone else blaming ultrasound on varies problems, please read up on your fact from peer reviewed articles. Last of all to the lady who is 26 please don’t despair for our generation (I am 23) as I find it embarrassing that you yourself know little if not nothing.

    • I’m curious… If it’s been determined that Doppler is either questionably safe or unsafe during the first trimester how has it been proven that it IS safe in the second or third trimester? It seems to me if there is a risk of damaging developing cells that risk would extend beyond the first trimester, just perhaps to a lesser degree. If you could point me to any literature or studies on this I’d greatly appreciate it!

  11. Well now I’m freaking out. I used a friends Doppler (Bistos) at 11 weeks for 30 minutes and never found a heartbeat, but now I am second guessing myself for using it for too long and for using it at all.

  12. I found some of the observations in this article to be both informative and thought provoking. I have wondered for years about the increased incidence of Autism in our children, and even asked my son (a physician) if there was any known link to ultrasound. My reasons for asking were based on my perception that the numbers of cases of Autism are much higher now than when he was born (early 80s), and I don’t recall that the use of ultrasound at that point was nearly as pervasive as it is now. Was Autism there and we just didn’t know what it was? Or is there really more children affected now than there was 30, 40 or 50 years ago?
    I had not considered the more powerful machines in use now, let alone the fact that heat might be generated, but it all make me wonder. Do we really just assume that subjecting a developing fetus to repeated ultrasound waves will have no adverse effects?
    The use of ultrasound is more prevalent in certain cultures and even in certain demographic groups. Does the incidence of Autism or other developmental conditions also appear in these same groups at a much higher level?
    I am a veterinarian that strongly believes in the use of US for diagnostic purposes given medical reasons. The young women that I employed in my practice that are pregnant seem to get a lot of ultrasounds, certainly a lot more than what I recall being done 30 years ago, and to my knowledge there are no issues with the fetus to explain the need.
    The “standard of care” is constantly changing as we learn more and develop more sophisticated diagnostic tests and equipment. When do we consider the adage “above all do no harm” and whether we inadvertently might be doing that without even knowing it?

    • I had my ultrasound today. The lady spent about 8 to 10 min in the baby’s heart. I came home and I felt pain in that specific area. I start Google if there some evidence about the harm of ultrasound, because I did not feel this before. I feel very angry and scary. Never let the person who is doing your ultrasound stay an one area for more than 15 seconds. I feel angry with this lady because she should know better.

  13. Nobody does ultrasounds for fun. For everything you do put it in the risk vs reward context.
    Driving can be risky too will that make you stay at home and abandon everything ?

    High risk pregnancies with placenta issues, single umbilical cord fetuses, IUGR and many many more warrant a frequent monitoring.

    if it is being prescribed without a strong reason or for a fun Saturday night activity then risk outweighs the reward.

  14. The current usage of ultrasound during pregnancy has the capacity to reveal significant, life-threatening abnormalities which can affect both mother and/or baby. Ultrasound is not only safe, it’s use is considered the standard of care. Suggesting anything else to pregnant women who are understandably concerned with their baby’s health is both irresponsible and dangerous.

    • Could you please expand; In discovering life-threatening abnormalities through ultrasound how will the health outcome of mother and baby be improved? (i.e. what kind of treatments will be done and at which stage of pregnancy)

      • A routine ultrasound can diagnose dangerous conditions such as an incompetent cervix which can lead to premature labor (sometimes before the fetus is viable). If this is discovered, doctors will either put in a cerclage or recommend bed rest for the rest of the pregnancy. It can also detect fibroids and abnormalities of the uterus and placenta which could require medical intervention. I think for those reasons it’s important to get at least the detailed ultrasound!

  15. Thank you, Chris, for sharing your knowledge and beliefs. And thank you, too — Tarek and others — who generously shared your knowledge and understanding of ultrasounds etc. And I so appreciate the kind and respectful tone used to share the information as well!

    I don’t have anything to add – at this point anyway – as I am just researching information in order to decide how to proceed with my own pregnancy. But I did want to say thank you, very much, to all those who shared.

  16. Excellent article and nice references. It is true that an ultrasound can create different complications in a human body, but for the tubal reversal patients, it is a necessary element, so what the other procedure should they choose to identify their tubal ligation surgery type.

  17. The World health organisation published this warning about ultrasounds:

    “The World Health Organisation stresses that health technologies should be thoroughly evaluated prior to their widespread use. Ultrasound screening during pregnancy is now in widespread use without sufficient evaluation. Research has demonstrated its effectiveness for certain complications of pregnancy, but the published material does not justify the routine use of ultrasound in pregnant women. There is also insufficient information with regard to the safety of ultrasound use during pregnancy. There is as yet no comprehensive, multidisciplinary assessment of ultrasound use during pregnancy, including: clinical effectiveness, psychosocial effects, ethical considerations, legal implications, cost benefit, and safety.”

      • Hi Lisa,
        I was doing preliminary brief research when I found that quote and didn’t think to take note of the source.

        I have just found a similar quote for you with the source from the WHO in collaboration with other organizations:

        t]here are several frequently quoted studies that claim to show that exposure to ultrasound in utero does not cause any significant abnormalities in the offspring. …However, these studies can be criticized on several grounds, including the lack of a control population and/or inadequate sample size, and exposure after the period of major organogenesis; this invalidates their conclusions….”

        Here is the source:

  18. Tarek,

    In one of your multiple comments, reiterating the same arguement, you do “note Dr. Kresser’s point about most [studies establishing ultrasound risk] having been done with the older machines”, but then proceed to completely ignore it. I think this is the entire point of his article, and it is valid.

    Also, he doesn’t have to be an expert to choose to err on the side of caution when our technology has surpassed our knowledge of its safety. He can voice these concerns as an intelligent individual with choices to make for himself.

    I remember the silly Mr. bean shows, when Mr. Bean would exclaim, “I don’t know Mr. Hands, it doesn’t look very safe! It didn’t take a Philadelphia lawyer to agree with Mr. Bean, and it doesn’t take one to see where Chris is coming from either. It is his right to point at the potential risk and a the absence of needed information, and to share his personal choice to forgo tests based on the simple fact that gynecologists themselves warn against overuse for the exact reasons that the as-yet unquantifiable risk of may cause negative outcomes. Is he being over cautious? With no established risk ratio, your guess is as good as anyone’s, and only time will tell.

    His point is but one voice. I for one appreciate that it isn’t left out of the discussion. Yours has also been made, heard and more than sufficiently indulged.

  19. My doctor uses the handheld fetal stethoscope at every appointment. It has a little speaker on it, so that we can all hear the heartbeat out loud. I am 17 weeks, and at today’s appointment, I told her I’d prefer that it not be used.

    She then convinced me to let her go ahead by telling me her machine used the lowest frequency (that to produce an image it would need to be much higher, but not for sound only), and that she would only use it for a very short period of time (she was done very quickly – maybe one minute?) She also agreed to use her stethoscope alone in future, without the additional handheld device, once the heartbeat can be heard that way. She also scared me a little by informing me that if the baby’s heartbeat were “off” in this listen, she would need to send me to the hospital for further testing.

    So now I’m back home and wondering, what exact frequencies are used in these hand held stethoscope monitors? Also, what can the medical system do if the baby’s heartbeat is “”off”? How much of this testing actually leads to useful intervention? I had three very early miscarriage and nothing could be done to prevent those…

    I did read that the 20 week ultrasound can reveal anomolies that are operable in utero – one article discussed the better outcomes for those babies with scoliosis operated on while still in the mother’s womb than for those for whom treatment was delayed until after birth. Are there a lot of these kinds of anamolies that can be detected AND resolved or pre-treated before birth? Are there enough benefits and/or positive results to justify the risk involved with multiple high frequency doppler tests?

    • Hi Ceylon, thanks for your interesting comments. Where can I find the information about treatments in utero? I would be very interested to read those. Also, I don’t understand that if these studies suggest benefits of operating in utero, then how come the large studies mentioned by Chriss have shown no benefits to pre-diagnosis of complications…?

      And I’m also interested in hearing more about the handheld stethoscope since I believe they use them at the birth-center I’m attending. From this article it would seem to be that they are among the highest of concern along with the Doppler…

  20. P.S. The rate of stillbirths according to one study done for Type 1 diabetics is 19.6%, which is 4-5 times higher than the percentage for non-diabetics. This study also indluded diabetics that were smokers as well as diabetics who did not manage their diabetes or control their blood glucose levels.

    I sincerely wish that information could be gathered only from those that did not smoke and also only from those that controlled their diabetes very well. (Those that has a hba1c percentage below say, 7 or 6 %.)

  21. I am a Type 1 diabetic and am 15 weeks pregnant with my first child. I have had all of the testing possible done including the first trimester nuchal translucency test. All of the results came back very excellent. My blood pressure is excellent. So far this pregnancy has been very easy. I am using a continuous glucose monitor and an insulin pump and am keeping a close eye on my blood glucose levels to keep it below a hba1c of 6%, looking to get it even lower as much as I possibly can, my goal is 5% (non-diabetic ranges are 4.3-5.8%). I am also exercising to maximize the size and health of the placenta. I desperately want to have a natural birth without an induction or c-section and am doing all I can physically do to make this possible. The OB/GYN is trying to force me into an induction and wants to increase the ultrasounds to every week beginning at week 20 and twice a week beginning at week 32. She is already doing them once every 2 weeks. I have done a lot of research and discovered that 5 mg of folic acid is recommended for pregnant diabetics since it has been found to reduce the risks and incidence of stillbirths. I asked my OB/GYN about it and she said she has never heard of this recommendation before. Mind you, I read about this in multiple places as well and went as far as to discover why this was recommended. It has astounded me that she did not know this and additionally did not look into this at all after I had shared this with her. I will be counting the numbers of the baby’s kicks per day as well. I am having an anatomy scan done at 18 weeks and a echocardiogram of the baby’s heart shortly thereafter. I admit I am uncomfortable about the idea of having so many ultrasounds done. I am wondering if I could just do the anatomy, echo and then allow them to do the ultrasounds 3-4 weeks before the delivery but none beyond that in between those tests and now? Even the ultrasounds can still miss a possible placental degradation. Is it possibly fine to avoid the anatomy as well? The frequency of all those ultrasounds just honestly feels like overkill to me and I do wonder if they are truly 100% safe or fine. If it truly is beneficial to do them however, and if I knew there was more of a reason beyond just monitoring and checking, I would be fine with it beyond the last 3-4 weeks worth of ultrasounds. It really bothers me that the doctor is trying to force me into an induction that may very well turn into a c-section if the induction fails. So far, everything is absolutely excellent and I have zero complications. To everyone here, could you share your thoughts concerning this if you have any?

  22. Having had a LEEP you are at higher risk for preterm delivery. The most accurate way of determining if the process of cervical shortening has begun ( prelude to labour) is ultrasound. When studies were done comparing a digital exam ( using fingers) to ultrasound in determining cervical length, the superiority of ultrasound was evident. If you truly feel more comfortable not having ultrasounds then the only option might be a vaginal exam, by the same OB every 2 weeks until 32wks of pregnancy. You will need to accept though that a shortened cervix may be missed until it is clinically evident i.e. too late, and that the risk of this would be losing an opportunity to potentially give steroids for foetal lung maturity in a time frame that might make all the difference between a good and bad outcome.

    (It is not inevitable that you will go into preterm labour; the risk is higher than normal though).

    I do not know any OB’s who would be happy to do this, but again I also know none of the good ones will ever compel a patient to do something she does not want.

  23. Hi Chris,

    Great articles, thank you for writing these.

    I had a leep procedure done a few months before I conceived and my OB says I will need to have an ultrasound every 2 weeks starting at 20 weeks. I truly do not want these ultrasounds but it doesn’t seem like I have a choice. Are there other ways of determining shortening in the cervix? If anyone else has had this experience, I would love to hear your thoughts.

    Thank you!


  24. 1. Not just because a study is published does it mean that it’s results are reliable. It is estimated that 90% + of published studies are of low quality and do not contribute anything to patient care/ knowledge

    2. Dating is necessary- it avoids deaths due to prematurity in circumstances where birth has to be induced for medical reasons, decreases the number of unnecessary inductions of labour ( and attendant complications of the intervention) and allows us to adequately counsel women whose babies may be too premature to survive in circumstances where for example premature rupture of membranes occurs. The entire speciality of OBGYN worldwide agrees with this, as do women unfortunate enough to have required intervention that depended on an accurate gestational age. If you disagree then I guess we all stand corrected.

    3. Medical schools and hospitals where doctors train are not sponsored by equipment companys, neither are we trained by them.

    Perhaps a little more research into the facts might be in order as if you are prepared to make sweeping generalizations based on ignorance of the reality re: training then I personally would doubt the veracity of the rest of what you have said. Then again what would I know as a trained OBGYN? After all I’m part of the conspiracy.

    4. There is no such thing as a free lunch. HRT, x rays etx are safe provided they are used correctly and in the right patients, but like anything in life there will always be someone who is harmed. Drink 4 liters of water a day and you will feel wonderful. Drink the same volume every hour and by hour 5 you will be dead of cerebral oedema . It wasn’t the water that was dangerous, it was how you used it that was.

    5. No one asked you to ‘blindly trust’ anyone but it appears you are doing so by believing everything my eminent colleague is saying.

    • Tarek, it is very hard to change medical practices once they become the “standard of care” no matter how much scientific evidence comes out showing a practice is harmful. Routine episiotomy is an excellent example of this. As a medical practitioner yourself, you must be feeling a certain amount of cognitive dissonance about the question of ultrasounds. The truth is it is very possible that we are grossly overusing ultrasound in obstetrics. Doing a scan at every visit has become the standard of care for many doctors who dismiss the idea that it is even possible that overexposure to ultrasound could be anything but benign. Pregnant mamas have come to expect scans, and it seems that women are getting upwards of six scans per pregnancy. No doubt you are aware of the work of Pasko Ravic, Ph.D./M.D. who has been conducting a 7-year-long ultrasound study on primates at Yale University. The best thing to do would be to contact him directly to discuss the results of his meticulous research, since they have not been published yet. There is mounting evidence that overexposure to ultrasound is causing brain abnormalities in some human fetuses. That must be difficult to think about, given your profession. But instead of remaining anonymous and getting into an internet debate, however useful it may be, it might be better to spend some more time with the scientists investigating this issue and looking at their theories, experiments, and results. I would be glad to have an off-line conversation about this by phone, Skype, or email. If you are interested in deepening your knowledge and understanding about this issue, please contact me.

      • Believe me I’m the last person who cares about ‘standard of care’ as I’m constantly questioning it.

        I think though we need to be a little more nuanced than to claim all ultrasound is harmful and hence should be discouraged or avoided, which it seems to me is the exceptionally unreasonable position being postulated. Evidence changes all the time in medicine and what was practised today is often abandoned tomorrow, revisited in 10 years and reintroduced sometimes with the previous research being rubbished as inadequate ( episiotomy being a great example as most of the large studies did not distinguish between midline and media lateral episiotomy and their different impact on anal sphincter injury and subsequent incontinence as it was much easier to not distinguish between them ).

        The evidence that continuous exposure to ultrasound is potentially harmful, secondary to the risks of tissue heating and cavitation is widely know , hence we are exhorted to limit the time taken to perform ultrasound and to avoid higher frequencies eg Doppler during organogenesis. No one except someone exceptionally ignorant of ultrasound physics would deny this. Furthermore long ultrasound studies with the probe placed directly over a particular tissue for a considerable length of time is associated with mechanical effects hence we tend to avoid doing this except when performing targeted anomaly scans, of which 2 at maximum need to be performed in pregnancy and only in those complicated by anomalies

        . Foetal brain injury, were it happening on a scale suggested would have manifested itself clinically in the form of specific organic brain disease. Where is the evidence this is happening? Cerebral palsy rates have been static since the 1960’s and there are multiple causes, theories and explanations for mental retardation, autism, epilepsy and other disorders that including heavy metal poisoning, teratogenic drugs, older maternal age, chromosomal anomalies, alcohol, drug ingestion, viral infection etc. Why is ultrasound now being victimised as though it were the last piece of the puzzle? Are the effects of co founders like the toxic chemicals found all over our planet e.g. Flame retardant materials in furniture being controlled for? Primate studies are all well and good, but with millions of women yearly in the US alone receiving ultrasounds and delivering healthy babies, with a widened social media presence and a media constantly searching for salacious scandal where are the cases that would prove beyond doubt that it is harmful? Are they perhaps being concealed by some conspiratorial group? Ultrasound has been used for over 60 yrs in medicine, in all age groups, at all stages of life and has an excellent safety record. I am actually very open to new ideas and never actually believe that anything in life is ‘settled once and for all’ but this whole idea seems to me terribly self-indulgent. We live in a society where patients will happily sue their OB anytime something is ‘missed’ , yet want 100% detection of all anomalies, a perfect, stress free ‘natural ‘ birth and everything to run smoothly . Anything that goes wrong must be someone’s fault, seems to be the logic. This is a Paradigm that cannot be perpetuated, especially when the tools we use to try to meet these unrealistic expectations are now being blamed for causing so e of the trouble. Why is the evidence of safety of ultrasound being ignored?

        The reality is there is no intervention of any kind whether drug, imaging or surgery that does not have the potential for harm implicit in it. This does not mean we should abandon those interventions, merely that we must study them thoroughly, use them wisely and stay away from idealistic nonsense of claiming something is ‘completely harmful’ or ‘completely harmless’.

        I look forward to the data you refer to being published in a peer-reviewed journal. Should it meet the standard required of papers purporting to establish causality and not association I will be more than happy to reconsider my position.

        On another note, using my first name in a public forum can hardly be construed as anonymity.

        All the best.

  25. To clarify certain misconceptions: 1. ” Dating” is the most important reason for performing an ultrasound in pregnancy. The biggest killer of babies is preterm delivery, something that cannot accurately be diagnosed if the exact gestational age of a pregnancy is known. It is not enough to have a regular period; studies have shown that ultrasound is more accurate for dating than is last menstrual period. 2. The second biggest killer of babies is congenital anomalies. These cannot be diagnosed without ultrasound and sometimes require several for confirmation. It just happens that at the same initial anomaly scan, sex is determined. This is important to many parents and hence to my mind is a ” medical” reason. 3. A paper presented by a colleague in Europe found that over 75% of ” low-risk” pregnancies subsequently became ” high-risk” so to suggest that some women deserve less care than others is naive at best. 4. IF your OB had this attitude then it is unacceptable, however there is always 2 sides to the story and I won’t pass judgement without both. 5. If memory serves me correct Dr. Northrup is not a radiologist, ultrasonographer or an Obstetrician . She is a Family Doctor, practically none of whom receive any ultrasound training during their residencies. I would suggest that unless you intend to take your car for repairs to your hairdresser, or your boiler to a carpenter that you look very carefully at who is delivering the ” evidence”.

    Millions of us all over the world regularly perform or order ultrasound for our patients. We are yet to see a single complication of ultrasound as used responsibly, like any thing else in life, it is safe. Pregnancy by itself is a risky physiological state, and whilst I agree that we should minimise risk, lets focus on reducing tangible risks before we obsess about theoretical risks.

    Just because a paper is published does not mean we should take its words as gospel, and unless an expert in ultrasound with research experience and proven credibility presents tangible evidence of harm, I would personally advise any pregnant woman to have an ultrasound as suggested by their OB.

    Contrary to popular belief, us OB actually care about our patients, and given that we spend 4 year at college, 4 years at med school, and at least 4-7 yrs training exclusively in our speciality I like to think we actually know what we are talking about. ” Primum non nocere” is the first principle of medicine, and that is something practically all of us live by.

    I would also suggest that anyone attempting to read the literature be trained in critical appraisal, epidemiology or have access to someone who is. If many doctors are unable to correctly interpret the literature after many years of training, with the greatest of respect then someone without the training attempting to understand the individual studies is like a person reading a foreign language with no idea what the words mean.

    Ultrasound is safe and has been established for over 60 years.

    • Dr. Northrup is an OB ->

      They are safe? I guess you didn’t read any of the studies linked above? That’s some contrary evidence right there. They used to say hormone replacement therapy, x-raying pregnant women, and even not washing hands between patients were safe but they weren’t! When it comes to my family’s health – blindly trusting people that have been trained by the very companies that produce these equipment and drugs and asking questions later is not good enough for me. If it’s not medically necessary (and no, “dating” is NOT) then I decline thank you very much.

  26. Thank you for a very thorough post on this subject and the links to studies. Dr. Northrup was the first person I heard say she refused ultrasounds in her pregnancies and since then I’ve been doing more research on it.

    First of all, no one is saying that ultrasounds shouldn’t be used when medically necessary or for high risk situations. I think the author is pretty clear that when the benefits outweigh the risks that it’s the smart choice. It’s when there isn’t a medical reason for an ultrasound – like dating, seeing the gender, or just “checking” – it is concerning in light of this evidence.

    I’m 12 weeks pregnant and when I had my first appointment with an OB (that I will not be returning to) she completely chewed me out for declining the ultrasound claiming that it was necessary they get the correct date and to check that I had a “viable” (in other words, alive) baby. She claimed the data was pretty clear that they are safe (but it’s not). All of her reasons for justifying ultrasound was about their convenience and saving them time and money – not about my and my baby’s health. Since then I found out that no one on staff there, not even the midwives, know how to use a fetoscope!

    This is very concerning when we are losing the power to make our own medical choices in the best interest of our and our babies’ health for their profit. Parents do not give informed consent to any procedures when they are not presented with the pros and cons (like listed above) and this needs to end.

    We are currently looking into natural birthing centers to deliver our baby. Hospitals are great and very important for emergency care – but otherwise I don’t feel very safe and cared for when their dollar and time saving is the bottom line.

    • Dina, like you I was very excited to be looking at birth-centers in our city, until I found out that they would be using the mobile fetal monitor every other contraction in the second stage of labor. Now I’m concerned that they are also using the hand held devices mentioned in the above article at every pre-natal visit. Talk about irony?

  27. Have there been any studies regarding effects on ultrasound technicians who do them all day? Does it have any effect on their fetus if they are pregnant?

  28. 1. Can an Ultrasound detect brain injury, dementia, blood clots, and the possibility of developing a stroke, as well as scoliosis, weak kidneys and bladder?

    2. Is an Ultrasound safer than an MRI Scan and CT Scan?

    3. If they use a gel to perform the ultrasound test, then how can they apply gel to the head to do this?

    4. This patient was involved in a motor vehicle accident and since developed a fear of these diagnostic machines such as CT Scans and MRI Scan. She fears that due to the high amount of radiation they are said to transmit in order to obtain the pictures, even though they are said to both work differently, that it may further aggravate her condition . She also has developed claustrophobia and cannot go inside these long, tight and narrow machines and expected to be kept there for an hour until they take their pictures, and does not want to be given any sedatives because she suffers from severe allergies to foods, chemicals and prescription drugs. She also is against having Glandolium Contrast which is said to cause permanent hardening of the muscles and kidney damage.

    I hope someone can give me a reply urgently because we need to know how we can treat her injuries.


    • The fact that left-handedness was higher for boys exposed to ultrasound in utero probably means that the ultrasound had an effect on the development of their nervous system. That’s a major red flag.

  29. As someone who experienced many years if infertility and then losses and 3 very high risk pregnancies, I appreciate every single ultrasound that I had most especially the one that saved my son from being stillborn.

    It’s also amazing to me that after taking 2 years to become pregnant at the age of 39 that you would not allow your wife to have an ultrasound. First, there are many abnormalities that can occur in a baby, more so at increased maternal age. Knowing about those issues before your baby is born and being in a facility where that little one can receive immediate care is of utmost importance. One in 100 babies have a congenital heart defect, a lot of which can be detected at a thorough 18-20 week ultrasound. Then that baby can be safely delivered in a hospital with a NICU where it has a much better chance of survival.

    Second, there are numerous issues which can occur with the placenta which would greatly endanger the life of the mother and potentially the baby. Placenta previs, placenta asccretia, IUGR of the baby are just a few. Knowing about those only empowers the mother to seek out the best care available for herself and her child

  30. In the mid 1970’s Sweden had investigated and found with their data that dyslexia was a prevalent outcome. Ultra sound scanning was stopped and only done where there was at risk to mother or foetus. There was a marked drop in dyslexia in Swedish children with the cessation of scanning. The scientific studies were available for all to read at that time.

    Why did the UK continue with scanning? Now dyslexia is rife!

    Dyslexics are extremely intelligent children who see the world in a different format to what we consider the norm to be. They find learning the conventional way difficult and not conducive to their way of thinking and learning.

  31. As an OBGYN I am definitely and aggressively in favour of patients being fully informed about everything done for them no matter how ” routine”.

    Most complications that occur in pregnancy occur in healthy women, more often than not who have no risk factors. That is the sad reality that many of us face.

    Ultrasound is one of the tools that we use to ascertain the health status of a baby. It should definitely be used for indicated purposes but to quote studies without putting the numbers in context, without further describing the background, the populations etc is to misrepresent them and their conclusions.

    Unexpected congenital anomalies, a dead baby, a baby undergrown ( IUGR), twins, a placenta whose location is abnormal or which is invading the uterine wall are examples of complications that occur in all women and that can only ever be diagnosed on ultrasound. By unreasonably spreading the idea that ultrasound is a potential danger when the large studies done over time suggest otherwise ( I note Dr. Kresser’s point about most having been done with the older machines) we are only decreasing the ability of anOBGYN to reassure a woman that her baby is well and to detect issues that can unexpectedly occur.

    Compare the theoretical risks of ultrasound to real risks of pregnancy e.g. 20% risk of miscarriage, 1-5% risk of preeclampsia ( complications can include the mother dying in extreme circumstances), 1-5% risk of diabetes in pregancy ( risks to both mother and baby ) among others. How can it now be said to be deleterious? Compare the potential risk of caffeine ( increased miscarriage rate noted in some studies), smoking ( increased miscarriage, low birth weight babies), being overweight ( increased risks of all complications) with ultrasound and ask yourself why is a theoretical risk being placed more at a premium than documented risks?

    Millions of women all over the world have ultrasounds daily. Where are the reports of anomalies that were caused by them? Or of babies that experienced a complication directly attributable to ultrasound? We live in a world where disasters like Thalidomide cannot be hidden anymore, where lawyers are trigger-happy and where patients thankfully no longer blindly follow their doctor’s advice. Events can no longer be concealed so where are they?

    If you want to know both sides of the story you must ask someone directly involved in the field and challenge their advice / “facts” with that of others, either also working in the field or whose education/ reading qualifies any opinion they may have. If a doctor specialising in disorders of the liver was to write a book on heart surgery, noone would take it seriously as that individual, no matter how informed theoretically, would lack the knowledge practically to inform their opinions. Family doctors do not do ultrasound hence I would view the “evidence” presented in the book referenced in the article with extreme scepticism.

    There is no such thing as a risk-free pregnancy. Birth is a natural process, but that does not stop hundreds of thousands of young and healthy women yearly dying in childbirth. We can only manage risk to a certain extent, but should not create a false dichotomy where one either chooses ” medicalised” or ” natural” pregnancy and childbirth. To imply that one or the other is ideal is patently ridiculous as one implies that all the advances of medicine have been futile and the other that medicine has all the answers, two positions which are extreme in nature and against the balance most of us seek in all aspects of our lives.

    • Due to the fact that ultrasounds could be causing a host of issue that can’t be directly linked back to the ultrasounds is enough of a reason for me to not want my babies being exposed to the heat, and high frequency waves. You are saying bc babies are being born healthy, then that is assuming the ultrasound hasn’t done damage to any of the internal workings. Would a slightly weakened immune system be apparent at birth? Or some mild-severe neurological problems? There are so many crazy new disorders and diseases with babies these days. There’s no evidence against ultrasounds bc there’s no testing. But personally, 100% of the babies of friends I’ve had who had multiple ultrasounds have had issues with sleeping as babies, and having worse than normal immune systems, babies that get sick ALL the time. And as toddlers they seem slightly autistic or “off” socially.. not enough for them to be considered autistic, but enough to see when all the kids get together, which ones are “different” my daughter who I only had one ultrasound with randomly got a perfect circle of eczema on the side of her knee after I stopped breastfeeding then it showed up in other areas on her legs. What I hear is that, oh that’s normal. The problem is that yes it really could be anything. It could be the result of the ultrasound damaging cells that were forming in her immune system and around her skin in those areas. But eczema is surely on the rise, and nobody can pinpoint it. I am anti ultrasound bc I would rather take the risks of the unknown anomalies. I believe I should be informed about proper nutrition to keep myself and babies healthy and then deal with any emergencies if they arise. If other people want the option of having a slew of ultrasounds, they should. But my decision to not want ultrasounds should not be treated as if I’m somehow endangering my “twin” babies. The evidence is not pointing to the safely of ultrasounds, but the fact that NOBODY knows. That unknown means something to me.

  32. contained in his article regarding Doppler being more dangerous as continuous vs. pulsed and whether more dangerous 1st trimester vs. 2nd trimester (when baby’s bone more developed).

  33. I find it quite disturbing that Chris failed to reply to two very good questions posed by other readers (Lotklear from Oct 2013 & Elizabeth from July 2011) regarding conflicting information c

  34. Great article. Have a great list of references as well. I cannot agree more with this article and some of the comments other mothers have mentioned.

    It is always a struggle to balance between “check to see if the baby is ok” and the potential damage these types of diagnostic tests may cause. The issue is that many people, and even doctors believe ultrasound devices are safe without really looking into this.

    A friend of mine had some bad experience as some of the mothers were mentioning about, and her story motivated me and two other engineering friends to start a project – providing a passive tool that allows expecting mothers to hear the baby’s heartbeat passively and therefore safe.

    I truly believe that many parents will gain benefits from this device. How does it work? Sound waves from your baby’s heartbeat are focused onto an ultra-high sensitivity microphone through a fetal stethoscope, and it then Interfaces with your smart phone device. This has allowed us to perform audio filtering in order to reduce ambient noise, thereby improving the sound quality of your baby’s heartbeat. It is a passive detection method, and the sound quality is significantly better than a normal fetal stethoscope, so you will still be able to hear the baby’s heartbeat as long as the position of the baby’s heart is facing outward.

    Find more here:

  35. Personal experience: (I had multiple ultra sounds with my youngest, because of high risk issues, but unrelated issue surfaced for this daughter later, I think due to ultra sounds)My daughter is now 25 (born 1988), and has had some of the issues surface discussed in the article! Plus when she turned 8 we discovered she had an arachnoid cyst. Although her growth issues surfaced in growing pains nearing the preteen years. She is 5 foot 10 now. But during growing years, I saw her litterally grow overnight at times, and experience great intense pain.
    The neurolgist thought the arachnoid cyst happened in-uteral (during pregnancy), but funny thing, we had multiple ultra scans checking to see if she my have any cranial hemmoraging like my other 2 babies. So I know she did not, reflectively what I have learned about troubles with arachnoid cysts, I suspect it may have manifested around 6 months old as I recall behavior incidences that happened at key times.. The Cavitaion concerns… well the nuerolgist had discovered her hearing had not fully developed (age 9), this is where the arachnoid cyct(s) are. So she had slow speach development, and had dexlexia. She does have some hearing, but where there are multiple sounds/noises it is difficult for her to single out and dicipher what someone is speaking to her. I.e. she or another person talking over a phone or cell phone is really frustrating for her if there are back ground noises on her side or whom she is speaking with. Or in an area where machinary is running, she has more trouble then others would, and can become very agrivated by such situations! Her stress levels elevate and become more problematic more then others under stress, even being overly exhausted can become a stress and it is important for her to get needed rest before making important decisions or addressing emotional topics.
    She is an awesome talented lady, with a beautiful spirit, but the handicaps as a result of this issue surely become problematic! We do know the better the diet, the better is life in every capacity, whole foods important! Lots of fresh raw fruits and veggies even better!!! I hope this experience of life learned from those affected by the affects will benefit another. If I had things to do over again, I would have only allowed 2 of those ultra sounds and even considered, especially if I had known then what I do about diet now, no ultra sounds, etc, I would have just eaten 80 percent raw fruits and vegetables, no meat and no dairy.

  36. Your sources indicate PULSED waves are more of a thermal risk and should be avoided. Your article states “Doppler ultrasound, which uses continuous rather than pulsed waves, has been shown to cause significant heating”. So which is more dangerous- Pulsed waves or Continuous waves. Further, my reading indicates Doppler can either be pulsed or continuous. Please clarify.

  37. Hi Chris,

    My husband and I are weighing whether to have an ultrasound scan. If I were to have one, I’d only have one.

    I’m at 17 weeks and have read on several web sites that the scan tends to be more/less dangerous depending on what stage of development the baby is at. What would be a safer window in which to have the scan based I guess primarily on brain development?

    I wish I had researched info before asking to have a doppler scan at week 14 🙁 My mom had told me to research the health risks of ultrasounds, but I was unaware that a doppler and ultrasound are similar devices, and I was in a country where internet was not readily accessible to me.

    I am 26 years old and I shock most of my peers when I say I’m not sure whether we’re going to have an ultrasound or not. I can’t believe how clueless/careless my generation is *sigh*


    • Thank you Jennifer. Of course now I am worried that any damage may be done since I’ve already had 5 ultrasounds. Is there anything I can do to reverse any negative effects going forward?

      • That’s an excellent question Sarah. The difficulty here is that every human responds differently to potential toxins. My grandfather smoked like a chimney but lived to 89 and never had a cough a day in his life, whereas Christopher Reeves’s wife died of lung cancer and never smoked. I think the best thing to do is what I am sure you are already doing: have the healthiest pregnancy you can by eating whole foods, exercising every day, reducing your stress levels (that one is so important and so often overlooked), and avoiding other sources of toxins (including edible food-like substances that aren’t really food and skin products that have harmful chemicals in them.) If you can check my book out from your local library, there is a lot in it about how to have a healthy pregnancy and childbirth. It’s called THE BUSINESS OF BABY: What Doctors Don’t Tell You, What Corporations Try to Sell You, and How to Put Your Pregnancy, Childbirth, and Baby BEFORE Their Bottom Line. There’s an entire chapter on ultrasounds.

      • To support Jennifer’s advice with regard to maximizing fetal recovery. Environmental hazards can inhibit recovery from ultrasound trauma, such as the unventilated gas stove, which is like a car idling in your kitchen. This is another political topic. Flu, colds, and virtually any disease can indicate stove or boiler exhaust poisoning. Venting is tricky as it always requires two vents, inlet and outlet.

  38. I am considered high need for monitoring due to loss of twins prematurely at 23 weeks last year and now a low lying placenta. I have had 5 ultrasounds already and numerous Doppler checks. I still have more ultrasounds scheduled but now I worry whether there any really any benefits to so many ultrasounds. It won’t change my outcome so should we just wait for one last ultrasound near the end of term? Always something to worry about! Thank you for sharing the information!

    • Sarah, I’m not sure whether this might help you feel a bit less concerned, but I had a friend who had a low lying placenta and had ultrasounds every month like you’re having, and her child is perfectly healthy, now an extremely bright 16 year old.

    • Hon, whilst i’m not qualified medically, i wanted to let you know about my neighbour who lost twins at 22 weeks. With her second pregnancy (also twins) she was hospitalised at 17 weeks and given ultrasounds every few days until she hit 27 weeks and the twins were born. They are now healthy, beautiful 4 year olds. I can’t make a comment about how many ultra sounds you should have in the future, but please don’t worry about the ones you have already had. I’m sure there is a healthy balance there somewhere. Please try and relax and all the best with your pregnancy!!

  39. I just learned that I must have failed my OGTT test as my doctor called to tell me they are recommending me to a gestational diabetes management specialist as I may be have GD. First of all, I have been following a fairly primal/paleo diet for the last two years. In pregnancy, I’ve been drinking a fruit and veggie smoothie (one banana, blueberries, strawberries, spinach, and kale – no added sugar) that I make myself. I don’t think I hit 75g of sugar in a day so of course I will have elevated blood sugar during the OGTT.
    I have been told that as part of the monitoring, they will be doing more ultrasounds and potentially prescribe medicine, neither of which I want.
    Am I really at risk of GD and need this monitoring? I am worried about the adverse affects of increased ultrasounds (I am at 24 weeks) as well as the impact on my wishes for a natural childbirth. Please advise!

    • Dear Donna,

      I would like to provide some of my understanding about Gestational Diabetes and regarding the Oral Glucose Tolerance Test(OGTT) that they have given you.
      First of all, I would like to start from the physiology of pregnancy. Pregnancy itself is undergoing a process where there is sudden change in the level of hormones in your body and the fluctuation in hormones itself will cause a physiological insulin resistance. In a another way, it means the level for your body able to to tolerate glucose will be less than a non-pregnant lady. With this insulin resistance developed(only in pregnancy), pregnant mothers will have higher blood glucose reading. Thats where the OGTT comes in. In OGTT, we perform this test as a guideline to find mothers predisposed to have Gestation Diabetes. Its just a guideline. Nothing is called a perfect test. However, we are trying to reduce the chance of GD because we would like to prevent some possible complications in the future, eg: Big baby, post delivery hypoglycemia in newborn, etc.
      Another thing, fruits contains fructose, which is still a simple sugar which body digest easily. The effects are similar with glucose. Plus, I believe you are not only drinking ONE smoothie for the WHOLE day perhaps? Glucose comes in lots of food. I do like it if you provide your meal list.

      Well, I would like to apologize with my limited knowledge as a medical student. However, please read more references and listen to both side of stories before coming to conclusions. I wish you have a pleasant pregnancy.

    • If your body was functioning properly you would NOT have an elevated (diabetic range) blood glucose after drinking the syrup for the test! This is bc your insulin takes care of it! Dont assume because you drink sugar that your bloodsugar skyrockets. It should elevate slightly. More than that is a dysfunction.

  40. Interesting…. I had a miscarriage right after my first ultrasound, which showed everything was normal (at 5 weeks). Left clinic, came home, started bleeding. Coincidence? Who knows, but next time I won’t let doc scan me until much later.

    • I had sever cramping for hours after my first ultrasound at 6wks. Never before that or since then. (25wks now) I had a trainee do the test, he couldn’t see enough so asked his supervisor to do another one, after which the supervisor also used a probe. So three tests in one sitting! I wish I had known earlier that we could choose our radiologist. I would love more info. on that for the future.

  41. I appreciate this article and the information you have presented. I’ve found that doctors are astonished, and often angered, if you tell them you do not want an ultrasound.

    There is one aspect of ultrasound danger that you did not dwell on in this article: it seems to cause excess migration of brain cells. An M.D. at the University of Louisville and an M.D. researcher at Yale University are investigating whether ultrasound exposure is the trigger for autism. (Autistic brains, we know from double blind studies, have 10-15 percent more minicolumns.)

    I explore this connection at some length in the book I have coming out in April called THE BUSINESS OF BABY (Scribner April 16, 2013).

  42. Interesting articles, thank you! I went to see my midwife today, I had decided not to have any ultrasound scans and told her that. I agreed that she could have a listen to the heartbeat. I stupidly assumed what she was using was a stethoscope – nope! A Doppler handheld, I spotted the name as she used it – I asked her to stop using it, but she’d already used it for a minute or so by then. I was furious! With myself for not being more forceful and asking exactly what it was, with my partner for not asking any questions at all, and with the midwife for using ultrasound equipment on me when I’d specified I didn’t want that. I realise one must be hyper-vigilant and informed at all times, and extremely assertive too, and asking all the right questions. It seems this has happened to other of your readers too. Must one stay ENTIRELY out of the system to avoid this kind of thing happening?!

  43. I thinks it’s absolutely prudent to be cautious about anything that may have consequences we can’t know about, however, if you are going to have a website with a slant that is likely to scare many expecting parents, you should at least ensure your “facts” are accurate. Pulsed-wave doppler is in fact more problematic than continuous wave doppler. Hand-held dopplers and the contiunuous monitors used during labour are continuous wave and they work by using very low power levels and I can find no information of safety concerns with that form of doppler. It is actually the pulsed waved doppler, which gives images and colours, that is much higher intensitiy; it’s often used in high risk pregnancies to evaluate arterial and venous blood flow through the placenta, and it is that kind of doppler that has the concerns re: heat, cavatation, and acoustic streaming.

    • So @ Jen – you feel a little caution cushioned with wrong information about pulse vs doppler- reflects that ultrasound with a trusted medical professional should’nt be a cause for concern?

    • I don’t think any of us have a problem with ultrasounds being used in high-risk pregnancies – when there’s already an indication of problems is exactly when ultrasound should be used.

      I like to assume that this was an honest misreading, but I’ve seen way too many people with an agenda to push “misunderstand” advice and then claim it’s too dangerous to follow.

  44. Hey moderator, feel free to *not* post my previous comment reply to the person who scolded you for typos. It was written in haste and may only further aggravate her. 😉 Thanks and thank you also for the great article! I am a doula and I appreciate this info, however minimal the risk may be I also like to err on the side of caution when it comes to unnecessary procedures.

  45. Thank you so much for posting this! I was completely unaware of these risks and because of problems with my last pregnancy my doctors have recommended I get more ultrasounds than normal if I get pregnant again.

    • Honestly, I see a lot of self-contradicting information that is bordering on inaccurate. For starters, as a medical student, I have learned that any animal testing that is conducted needs to be taken into account that their bodies and chemical compositions are somewhat different from the human body. Any testing completed on animals should be taken with caution since humans can have different reactions than what the animals had when testing the effectiveness of medical devices (in this case) or the use of medications for treating disease.

      Secondly, as Mommy Theorist has said, typos are a big no-no when writing scientific articles. As a medical student, we are told that you have to carefully write out your papers and make sure they are proof-read before submitting work. This is to get you used to checking (and double checking your work) so that you do not make any mistakes. Any mistakes made on patient charts can be very bad. Especially if your quality of care should ever be questioned. Any mistakes made on patient charts can be used against you in a court of law should you be faced with a law suit.

      Third, you say in the article that ultrasounds are bad for the developing fetus. Everything someone does can have positive and/or negative effects on a fetus. It’s not different from smoking, taking over-the-counter medications for minor ailments, hot baths, or even simply breathing city air. However, you made a comment in the comments section that ultrasounds have very small risk and that one should not have to worry.

      All in all, what I am trying to say is that if you decide on writing an article on the effects of ultrasound on fetal babies, then one should present both the positive and negative effects of ultrasounds. This article is shown to have multiple biases and that in of itself can be a bad thing as it can show readers that you are only interested on presenting only one side of the story.

      Wishing you the best of luck in your future articles.
      Sincerely yours,
      Concerned Med. Sonography Student

      • I think he did talk about both the positive and negative… his concerns seem genuine, legitimate and unbiased to me, while yours are obviously going to be biased because you’re a med sonography student, and if you open your mind to the possible negative side-effects, your whole career could be out the window. Sounds like you’re defending your career choice to me.

  46. As a mom who hopes to have more children, I really value the information presented in this article. However, as an editor, I see several typos that should be corrected. It’s important to know that an author presenting scientific research has taken the time to carefully proofread hIs work. It’s hard to trust the content when quality has not been attended to. I see this a lot and recommend professional proofreading services when disseminating information that is this valuable and important.

  47. Hello Kris. I have a quick question for you. I said no to all ultrasounds and we made that decision even before i got pregnant. I had no idea a doppler uses an ultrasound wave and when i asked my doctor about what that device really is in response she said its just a microphone, 3 month later i find out it does use ultrasound waves. I feel terrible about it and do not trust my doctor and will not go back to her. I am 26 weeks now and the last time she used a doppler on me was last week. I am very concerned about it cause she used it 4 times. Should i be worried?

    • Katie: I don’t think there’s any cause to worry. Keep in mind that we’re talking about very small increases of risk here, and the vast majority of women who get multiple ultrasounds and dopplers have no issues. I’m just a fan of being as cautious as possible.

  48. I had a miscarriage in January and got pregnant again in May. Because I was/am considered high-risk, I had an ultrasound at 8 weeks (which the insurance company won’t cover anyway cos it’s too early). I have since had two fetal heart rate monitoring two weeks apart. What are your thoughts on that. At this stage, I’m willing to talk my husband out of having any more scans if it’s going to put our baby at any kind of risk no matter the magnitude. Coming from Africa (now in the US), I can testify that people have survived without it an still do have healthy babies. If I don”t need it, i wont have it.

  49. Chris, my wife was 39 when she was pregnant with our daughter. At that time (1997) we followed all the doctor’s advice. She had ultrasound, where we found out we were going to have a daughter. She also had amniocentesis. I’d be curious what you think about that. Maybe another blog post 🙂

    Hope all goes well, with the pregnancy and delivery. Very exciting 🙂

  50. Chris, I read this post immediately AFTER our 5 child’s ultrasound yesterday afternoon. Nice timing 🙂 All I can say is YIKES. My wife will be turning 35 before delivery so there is pressure for interventions. However, we’ve done well with 3 VBAC’s after our first child’s somewhat urgent c-section (breach). No drugs either. I will share that there is an increasing interventionist mentality creeping into America’s birthing experience – even in the 9yrs since we started prenatal care. Many people thought it was quaint we didn’t find out the sex of our first child. Now, they are verging on angry. The tech told us about 90% find out now and that she certainly saw a recent increase.
    My advice to those facing medical births in hospitals is to find a good midwife and doula – at least for the first couple births. It’s too easy to cede authority to medical professionals when personal emotions are involved, and their objectives are significantly different from the parents’.

  51. Also, I appreciate that you mention the undue stress that could cause it’s own problems. The stress on the mother who may not know if her baby is ok- would potentially be outweighed by the benefit of the ultrasound or doppler verifying that all is well with her growing child. It goes both ways on this topic!

  52. Can you clarify one thing for me, in your recommendation, you state, “Minimize exposure intensity (i.e. avoiding Doppler during the first trimester especially).” During the first trimester especially, but from the previous information, it seems as though the doppler would be more risky in the second and third trimester because of the bone formation that is already present in the fetus. ” The risk of inducing thermal effects is greater in the second and third trimesters, when fetal bone is intercepted by the ultrasound beam and significant temperature increase can occur in the fetal brain.”

    Also, I want to clarify- this includes the doppler used for hearing fetal heart-tones?

    How do you know if the ultrasound is done using doppler continuous waves vs. the waves that are seconds apart?

    Thanks for putting all of this information into one (two) articles, that I can easily share with others.

  53. Yes, the electronic fetal monitor is probably the worst form of ultrasound because (in most hospitals) women have it ALL THE TIME (hours and hours and hours), and (unlike the ultrasound scan), it is a continuous form of ultrasound! Eek! And, beyond that, no studies have been done that have proven the benefits of the electronic fetal monitor (because there are none) over intermittent fetal monitoring (with a, ahem, Doppler, or fetascope, which you’re going to find in a hospital setting). The only thing the electronic fetal monitor has proven to do is to increase the incidence of c-sections when it is used.

    That being said, although most hospitals have women wear the EFM throughout labor, if a woman has the knowledge to, she can ask that it be removed (although, most hospitals will still require an initial 15 minute strip upon checking in).

    • The problem is a mom must have continuous monitoring if she takes any drugs at all. Epidurals/pitocin can be very dangerous to babies so it is important to get the readouts. In my area, we have a 40% induction/augmentation rate and a 95% epidural rate. But otherwise, I agree…totally unnecessary. I had no interventions so my doctor said I only needed 5 minute strip per hour. Which was done very easily and without me hardly noticing it.

      • EFM is not a reliable source of information about the baby’s well being. I cannot remember the exact statistics, but it very, very often provides a “false positive” (that something is wrong when it in fact was not) and other times the EFM will indeed miss actual distress. These facts are alarming and surely contribute to today’s obscenely high c-section rates. It is a poor diagnostic tool, even when drugs are used. If it was accurate, yes we should use it in moderation when a women has had interventions. But since it is not, why are doctors and nurses so glued to those read-outs?

  54. Did you have any trouble getting the health care provider to go along with your wishes.I was wondering how great the pressure to have a routine ultra sound is.

    • We haven’t interacted with the medical establishment during our pregnancy. We’re having a home birth with a midwife, and she supported our decision not to have an ultrasound.

    • I had heard of several friends w/ problems w/ this. Plus, I was “old”. But I had no problem. I explained to my doctor that we would not abort our baby if anything was wrong and considering the stress of “false positives” I saw no need to proceed. I picked a prolife doctor who would not pressure me about fetal testing/termination.
      The hard part is avoiding the heart checks w/ the hand held doppler. I brought my own fetoscope and the doctor gladly used it. Keep in mind, many doctors/mw may not know how to use a fetoscope, so you’ll have to bring along some instructions!

  55. Mike – Fetal heart rates taken during an ultrasound are pulsed and the monitors used in the doctors office and during labor are contiuous wave – Both are two different kinds of ultrasound doppler. I am a ultrasound sonographer registered with the ARDMS

    • I’m hard pressed by this data that I assume is gathered from reputable research.
      My singleton pregnancy was high risk and I had six or so scans. She is a healthy three year old today.
      My twins were treated as a modi pregnancy and at the very first scan a size difference was detected.
      I find it offensive when you speak of iugr and not use the correct name Intrauterine Growth Restriction. If my daughters did not have 20+ scans I would not have them here with me today.
      This article is dangerous for women in high risk pregnancies who need to undergo ultrasounds consistently for the sake of their unborn child(ren).
      This study has no merit when nearly every pregnant woman out there will have had at least a scan during her pregnancy. Until you can find a controlled group that has never underwent an ultrasound these findings are a dangerous accusation.

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