Prenatal Ultrasound

The use of ultrasound has dramatically increased in prenatal care. Its safety and efficacy are still highly questionable. Even the FDA says, "While ultrasound has been around for many years, expectant women and their families need to know that the long-term effects of repeated ultrasound exposures on the fetus are not fully known."

Most studies and authorities recommend that ultrasound is safe only when "medically necessary". The question really comes down to personal practitioner selection: "what warrants medical necessity?" Here is where interpretation is vast and undefined. While ACOG recommends that ultrasound examinations be done for specific reasons, such as a suspected ectopic pregnancy, a possible miscarriage or detection of possible birth defects, many physicians include one examination as part of routine care, at 18 to 20 weeks of pregnancy. The March of Dimes Birth Defects Foundation estimates that 70 percent of American women have at least one ultrasound examination during their pregnancy.

Perhaps a more prudent approach would be to define medical necessity as "life saving" and forgo prenatal ultrasound procedures for less relevant reasons. The original axiom of medicine "first do no harm" should always beconsidered when determining "medical necessity" for ultrasound.

" Lack of risk has been assumed because no adverse effects have been demonstrated clearly in humans. However, other evidence dictates that a hypothetical risk must be presumed with ultrasound. Like-wise, the efficacy of many uses of ultrasound in improving the management and outcome of pregnancy also has been assumed rather than demonstrated, especially its value as a routine screening procedure."

In accordance with medical protocol, the safety and efficacy of prenatal ultrasound has not yet been proven via peer reviewed research. On the contrary, current studies are cautioning its use. Prenatal ultrasound, therefore may even be considered, "experimental and investigational".

Concerned with nerve system stress, doctors of chiropractic are always on the look out for procedures that may cause more damage than benefit. Now a new study presents data we have suspected all along: ultrasound may affect brain development.

Ultrasound Can Affect Brain Development

A new study warns, exposure to ultrasound can affect fetal brain development. Head researcher Pasko Rakic, chairman of the neurobiology department at Yale University School of Medicine. Although Rakic says, "Our study in mice does not mean that use of ultrasound on human fetuses for appropriate diagnostic and medical purposes should be abandoned" he did, however add that women should avoid unnecessary ultrasound scans until more research has been done.

The study, funded by the National Institute of Neurological Disorders and Stroke revealed that when pregnant mice were exposed to ultrasound, a small number of nerve cells in the developing brains of their fetuses failed to extend correctly in the cerebral cortex. The paper added that the since the developmental period of these brain cells is much longer in humans than in mice, that exposure would be a smaller percentage of their developmental period. However, the authors also made it clear that brain cell development in humans is also more complex than in mice and with more cells developing, the chances of developmental mishaps could be increased.

In Rakic's study, pregnant mice were exposed to ultrasound for various amounts of time ranging from a total exposure of 5 minutes to 420 minutes. The brains of the newborn baby mice were studied and compared with those of mice whose mothers had not been exposed to ultrasound.

The study of 335 mice concluded that in those whose mothers were exposed to a total of 30 minutes or more, "a small but statistically significant number" of brain cells failed to grow into their proper position and remained scattered in incorrect parts of the brain. The number of affected cells increased with longer exposures.

Obstetric ultrasound biological effects and safety.

J Obstet Gynaecol Can. 2005 Jun;27(6):572-80.

OBJECTIVE: To review the biological effects and safety of obstetric ultrasound.

OUTCOME: Outline the circumstances in which safety may be a concern with obstetric ultrasound.

BENEFITS, HARMS, AND COSTS: Obstetric ultrasound should only be done for medical reasons, and exposure should be kept as low as reasonably achievable (ALARA) because of the potential for tissue heating. Higher energy is of particular concern for pulsed Doppler, colour flow, first trimester ultrasound with a long transvesical path (> 5 cm), second or third trimester exams when bone is in the focal zone, as well as when scanning tissue with minimal perfusion (embryonic) or in patients who are febrile. Operators can minimize risk by limiting dwell time, limiting exposure to critical structures, and following equipment generated exposure information.


1. Obstetric ultrasound should only be used when the potential medical benefit outweighs any theoretical or potential risk (II-2A).
2. Obstetric ultrasound should not be used for nonmedical reasons, such as sex determination, producing nonmedical photos or videos, or for commercial purposes ( III-B).
3. Ultrasound exposure should be as low as reasonably achievable (ALARA) because of the potential for tissue heating when the thermal index exceeds 1. Exposure can be reduced through the use of output control and (or) by reducing the amount of time the beam is focused on one place (dwell time) (II-1A).
4. All diagnostic ultrasound devices should comply with the output display standards (MI and TI) (III-B).
5. When ultrasound is done for research or teaching purposes, exposed individuals should be informed if either the MI or TI are greater than 1 and how this exposure compares to that found in normal diagnostic practice (III-B). 6. While imaging the fetus in the first trimester, Doppler and colour Doppler should be avoided (III-B).

Does Ultrasound Improve Perinatal Outcome?

Many clinicians advocate routine ultrasound screening during pregnancy to detect congenital anomalies, multiple-gestation pregnancies, fetal growth disorders, placental abnormalities, and errors in the estimation of gestational age. However, it is not known whether the detection of these conditions through screening leads to interventions that improve perinatal outcome. The rates of preterm delivery and the distribution of birth weights were nearly identical in the two groups. The ultrasonographic detection of congenital anomalies had no effect on perinatal outcome. There were no significant differences between the groups in perinatal outcome in the subgroups of women with post-date pregnancies, multiple-gestation pregnancies, or infants who were small for gestational age. Screening ultrasonography did not improve perinatal outcome as compared with the selective use of ultrasonography on the basis of clinician judgment.

Ewigman BG, Crane JP, Frigoletto FD   Effect of prenatal ultrasound screening on perinatal outcome   N Engl J Med. 1993 (Sep 16);   329 (12):   821-827

Another study from Norway looks at outcomes of antenatal ultrasound diagnosis in thirty-six children with serious congenital problems. It sought to determine how many of the problems were detected by ultrasound before birth, and whether outcomes were better when the problem was known before birth than for babies where the problem was missed on the ultrasound and not seen until after delivery. The women had had an average of five scans, but the average was seven in women who had a problem detected. Only two of eight congenital diaphragmatic hernias were picked up on ultrasound, half the cases of abdominal wall defects (six our of twelve), five of thirteen cases of meningomyelocele and none of the three cases of bladder extroversion.

All thirteen babies with prenatal diagnosis were delivered by cesarean section. Nineteen of the twenty-three with postnatal diagnosis had an uncomplicated vaginal delivery. Those with prenatal diagnosis had shorter gestational age (about two weeks), lower birthweights, and slightly lower Apgar scores. Three out of thirteen (23 percent) died compared with one out of twenty-three (4 percent) of those diagnosed after birth.

AIMS Journal, Vol. 10 No. 2

Does the Exposure to Ultrasound Relate to Delayed Speech in Children?

The purpose of this study was to determine whether there is an association between prenatal ultrasound exposure and delayed speech in children. The results showed that the children with delayed speech had a higher rate of ultrasound exposure than the control subjects. The findings suggest that a child with delayed speech is about twice as likely as a child without delayed speech to have been exposed to prenatal ultrasound waves The authors concluded that an association between prenatal ultrasonography exposure and delayed speech was found. If there is no obvious clinical indication for diagnostic in-utero ultrasonography, physicians might be wise to caution their patients about the vulnerability of the fetus to noxious agents.

Campbell JD, Elford RW, Brant RF   Case-control study of prenatal ultrasonography exposure in children with delayed speech   CMAJ 1993 (Nov 15);   149 (10):   1435-1440

Does Diagnostic Ultrasound affect Mylenation?

Neonatal rats 3 to 5 days of age were exposed to the ultrasound beam from a medical ultrasound imaging system. Dorsal nerve roots were examined by electron microscopy. Comparison between exposed and sham-exposed controls revealed disruption of the nodes of Ranvier attributable to ultrasound. Morphologic changes ranged from vacuole formation in the paranodal region to frank demyelination and were still evident after 24 h of recovery. Rats of this age are at a stage of myelination similar to that of a human fetus 4 to 5 months. The ultrasound intensities used in this study are consistent with those used for human imaging (SPTA 0.135 mW/cm2, SATA 0.045 mW/cm2, SPTP 8.7 W/cm2, SPPA 1.9 W/cm2), but the relevance of these findings to clinical ultrasound will require further study.

Ellisman MH, Palmer DE, Andre MP   Diagnostic levels of ultrasound may disrupt myelination   Exp Neurol. 1987 (Oct);   98 (1):   78-92

Does Ultrasound Cause Genetic Damage?

After a single exposure to diagnostic ultrasound there are long lived effects on the DNA of the cells, on the behavior of the cells, and on cell growth that persists for many generations. These are changes in cell structure that have persisted over 10 generations The results confirm previous findings indicating that ultrasound of diagnostic intensities can affect the DNA of animal cells.

Sister chromatid exchanges in human lymphocytes after exposure to diagnostic ultrasound   Science 1979 (Sep 21);   205 (4412):   1273-1275

Ultrasound in the diagnostic range appears to cause detectable effects on DNA and growth patterns of animal cells.

Liebeskind D, Bases R, Elequin F   Diagnostic ultrasound: effects on the DNA and growth patterns of animal cells   Radiology 1979 (Apr);   131 (1):   177-184

Does Ultrasound in Labor have an Adverse Effect on Maternal Red Blood Cells?

Blood samples were taken before and after Doppler monitoring. There was a trend toward increased fragility in patients exposed continuously for more than seven hours.

Doppler ultrasound and maternal erythrocyte fragility   Obstet Gynecol 1983 (Jul);   62 (1):   7-10

Risks of Ultrasound Scanning by Beverley Beech

  • Davies:   16 perinatal deaths compared with 4 perinatal deaths in the control group
  • Lorenz:   Preterm labour was more than doubled in the ultrasound group--52% compared with 25% in the controls.

I do not agree with the statement that "a lot of embryos have been exposed to ultrasound over the last 25 years with no documented ill effects." Lieberskind's research indicated changes in cell structure that persisted over 10 generations and although researchers attempted to rubbish the research it was repeated by other researchers, and now we have research from Ireland that also shows affected cells.

There is a widespread assumption that ultrasound is beneficial, yet there is no evidence that infant outcomes have been improved by routine ultrasound examinations. Researchers have enthusiastically focused on what ultrasound could find but have paid little or no attention to the potential adverse long-term effects. As a result, despite ultrasound being enthusiastically used over the last 30 years, there is no good research that addresses the anxieties that ultrasound may be responsible for dyslexia, learning difficulties and behavioral problems.

The Saari Kempaainen study revealed that 150 women were diagnosed as having placenta previa; when they got to term only 4 women actually had it. In the control arm the women who were not exposed to ultrasound also had 4 women whose placenta praevias were discovered when they went into labour. Both sets of women had caesarean sections and there was no difference in outcomes. The researchers did not investigate the amount of stress a diagnosis of placenta praevia could have caused in the 146 misdiagnosed women. This research shows that early diagnosis of placenta praevia is irrelevant and a complete waste of time, yet doctors and midwives persist in telling women they have low lying placentas.

A study by Jahn revealed that out of 2,378 pregnancies, only 58 of 183 growth retarded babies were diagnosed before birth, and 45 fetuses were wrongly diagnosed as being growth retarded when they were not. Only 28 of the 72 severely growth-retarded babies were detected before birth. Furthermore, the diagnosed babies were more likely to be delivered by caesarean section (44.4%) compared with 17.4% for the babies who were not small for dates. If a baby actually had IUGR the section rate varied hugely according to whether it was diagnosed before birth (73.1% sectioned) or not (30.4%). Preterm delivery was 5 times more frequent in those whose IUGR was diagnosed before birth than those who were not. The average diagnosed pregnancy was 2.3 weeks shorter than the undiagnosed one. The admission rate to intensive care was 3 times higher for the diagnosed babies. This important study provides further evidence that scans are not benefiting babies or those mothers who were subjected to caesarean sections.

This Article was originally printed in Midwifery E-News at:
Scroll down to "4) Risks of Ultrasound Scanning"


Davies JA, Gallivan S, Spencer JA   Randomised controlled trial of Doppler ultrasound screening of placental perfusion during pregnancy   Lancet 1992 (Nov 28);   340 (8831):   1299-1303
Jahn A, Razum O, Berle P   Routine screening for intrauterine growth retardation in Germany: low sensitivity and questionable benefit for diagnosed cases   Acta Obstet Gynecol Scand. 1998 (Jul);   77 (6):   643-648
Liebeskind D, Bases R, Elequin F   Diagnostic ultrasound: effects on the DNA and growth patterns of animal cells   Radiology 1979 (Apr);   131 (1):   177-184
Lorenz RP, Comstock CH, Bottoms SF   Randomized prospective trial comparing ultrasonography and pelvic examination for preterm labor surveillance   Am J Obstet Gynecol 1990 (Jun);   162 (6):   1603-1607
Olsen O and Clausen JE   Routine ultrasound dating has not been shown to be more accurate than the calendar method   British Journal of Obstetrics and Gynaecology 1997 (Nov);   104:   1221-1222
Saari-Kemppainen A, Karjalainen O, Ylostalo P   Ultrasound screening and perinatal mortality: controlled trial of systematic one-stage screening in pregnancy. The Helsinki Ultrasound Trial   Lancet 1990 (Aug 18);   336 (8712):   387-391
Taskinen H, Kyyronen P, Hemminki K   Effects of ultrasound, shortwaves, and physical exertion on pregnancy outcome in physiotherapists   J Epidemiol Community Health. 1990 (Sep);   44 (3):   196-201

Other Websites/ Articles For Making Informed Choices about Ultrasound:

Ultrasound: Weighing the Propaganda Against the Facts
Another, very complete, well referenced article by Beverly Lawrence Beech can be found in Midwifery Today Archives:

Prenatal Testing: Ultrasound Safety and Accuracy
A thorough and infomative article on ultrasound.
Read it here:

How Sound is Ultrasound?
Read it here:

On the "safety" amd "usefulness" of prenatal ultrasound
Read it here:

Screening Ultrasonography in Pregnancy
Read it here:

Excerpt from the National Institutes of Health Consensus Development Conference Statement -- February 6-8, 1984

Think Ultrasound for Babies Is Safe ?
Article by Leigh Dundass

News Flash:  Research shows ultrasounded populations have a quadrupled perinatal death rate, increased rates of brain damage, dyslexia, speech delays, epilepsy, learning difficulties, and a 32% increase in left handedness (which is thought to be caused by brain damage).

  • Perinatal death rate quadrupled in ultrasounded group.  (2,475 woman study by Davies et al., 1993); Midwifery Today .
  • Ultrasounded babies more likely to develop epilepsy and learning difficulties.  Ultrasound Abstracts
  • Males babies exposed to two or more ultrasounds were 32% more likely to be lefthanded (which is thought to be caused by brain damage).  Ultrasound Abstracts
  • Four hours after ultrasound, cell death doubles and rate of cell division drops by 22% in mammals and researchers believe results same in humans.  Ultrasound Abstracts
  • Risk of miscarriage significantly increased among women who perform ultrasound more than 20 hours a week.  (Taskinen et al., 1990); Midwifery Today .
  • Babies who had serious problems and were ultrasounded died more often than non-ultrasounded babies with serious problems.  Midwifery Today
  • Ultrasounded babies who were growth retarded were three times more likely more likely to be admitted to ICU than non-ultrasounded babies who were growth restricted.  Midwifery Today
  • Preterm labor more than doubled in ultrasounded women.  (Lorenz et al., 1990); Midwifery Today
  • Researchers who developed ultrasound admitted possibility of hazard from ultrasound and said that it should never, ever be used on babies under three months.  Midwifery Today
  • Cells exposed to single dose of ultrasound behave abnormally ten generations after insonation.  Midwifery Today
  • Even if the above stats don't give you pause, how about the fact that ultrasound measures 100 decibels in utero - that's the equivalent of having your infant stand on a subway platform as a train comes roaring in and screeches to a halt - for the 20 or 30 or 60 minutes it takes for your doctor to do your ultrasound!!!  New Scientist .  As one writer notes, if you've ever heard of on opera singer breaking a sheet of glass with her voice, that is an example of what just one slow sound wave can do . . . but ultrasound uses ultra high frequency sound waves which bombard the child at an extremely high rate of speed.  New Scientist.

Perhaps most ironic and compelling is this quote from one of Yale's MD elite (Dr. Kenneth Taylor, M.D., Professor of Diagnostic Radiology and Chief of the Ultrasound Section at Yale University School of Medicine) who states:  "I would not let anybody get near my infant's head with a transducer [ultrasound wand] . . ."  A Prudent Approach to Ultrasound Imaging of the Fetus and Newborn by Kenneth Taylor, M.D.

Additional Articles From Mothering Magazine:

Ultrasound, Denisce DiIanni,   24:27
Ultrasound: More Harm than Good?, Marsden Wagner,   77:50
Ultrasound Hits Bubbles (GN),   45:81

Mothering article reprints are $3.00 each. You may order a copy with your credit card by calling 505-984-6292 or by fax 505-986-8335. If you prefer, you may submit your request in writing accompanied by your payment to: Mothering, P.O. Box 1690, Santa Fe, NM 87504.

Finally: therapeutic ultrasound has its risks as well:

  • Taskinen: A significant increased risk of spontaneous abortion amongst physiotherapists who use ultrasound for at least 20 hours a week and deep heat therapies for more than 5 hours a week.