A Website for Exploring the Topic

Could prenatal ultrasounds be a major contributor to the increase in autism?

This website is a repository of information related to the hypothesis. Over 60 papers and articles are listed and linked on the Evidence page and are referenced throughout the website.

Is prenatal ultrasound safe? Nobody knows. The allowable intensity of prenatal ultrasound was increased 8-fold in 1992 without testing for safety then or since. The American Institute of Ultrasound in Medicine (AIUM) is designated by the FDA as the regulatory body. The safety statement on the AIUM website states clearly that the AIUM does not know if the high-intensity levels of the last 25 years are safe. This is the entire statement:

Conclusions Regarding Epidemiology for Obstetric Ultrasound

Based on the epidemiologic data available and on current knowledge of interactive mechanisms, there is insufficient justification to warrant conclusion of a causal relationship between diagnostic ultrasound and recognized adverse effects in humans. Some studies have reported effects of exposure to diagnostic ultrasound during pregnancy, such as low birth weight, delayed speech, dyslexia, and non-right-handedness. Other studies have not demonstrated such effects. The epidemiologic evidence is based primarily on exposure conditions prior to 1992, the year in which acoustic limits of ultrasound machines were substantially increased for fetal/obstetric applications.

2018 Video. Researcher David Blake recently completed this video presentation on ultrasound side effects and safety issues: https://www.youtube.com/watch?v=5p7tNt1QIc0

Is prenatal ultrasound safe? Nobody is checking. In April 2014, the National Institute of Environmental Health Sciences of the NIH held a virtual forum “Autism & the Environment.” The panel of 6 experts commented on the status of research into environmental causes for autism spectrum diseases.

Why prenatal ultrasound, the most obvious change in the environment of gestation, is not being investigated as a possible cause was addressed in the last minute of the forum. It is at 55:45 on the youtube video.   For a transcript of that portion, click here.

What other environmental changes are suspects? For a presentation covering most of the possible environmental causes, read the slide text from the 2010 report to the Interagency Autism Coordinating Committee (IACC) of the Dept of Health & Human Services: The Elephant in the Room.

Unsafe? The burden of proof should fall onto those who claim prenatal ultrasound is safe rather than those who say it is unsafe. This website has no references to studies showing prenatal ultrasound to be safe for the fetus because prenatal ultrasound has never been proved safe. Although most children appear to have had no adverse reactions to typical prenatal ultrasound exposure, it is possible some fetuses are affected by factors such as genetic predisposition, operator error and machine inaccuracy. It is also possible that during certain periods of development, the brain is vulnerable to even the approved exposure levels of ultrasound.

Recent US Research
September 2016 – Researchers affiliated with the University of Washington concluded in a study of autistic boys that an ultrasound scan in the first trimester correlates to more severe autism symptoms.60 The research was prompted by an hypothesis that a trio of factors – genetically predisposed brain at a critical time in development is exposed to a stressor – was a primary cause of autism.25 For the 2016 study, an ultrasound scan was the stressor. The first trimester was found to be a critical time. The study did not consider whether the ultrasound exposures later in a pregnancy caused the less severe autism.

Chinese Research
A Chinese study published in January 2015 reports significant physical effects on the brains of lab rats as well as learning and memory effects.58 This is not new. Click on Key Points 8, 50 and 59 on the Evidence page for earlier studies dating back 20 years which have similar results. There is a new book with more information on research in China conducted on human fetuses scheduled for abortion that shows damage to the immune system, brain and kidneys. The book – 50 Human Studies, in Utero, Conducted in Modern China, Indicate Extreme Risk for Prenatal Ultrasound: A New Bibliography by Jim West – can be bought from Amazon.

Optional Procedure. Examination with ultrasound is optional and of little value in a normal pregnancy. Since prenatal ultrasound has never been proved safe and while research continues into the causes of increased autism, it would seem prudent to avoid such exposures.

A Summary of the Basic Facts

Autism Spectrum Disorder. Autism is most accurately known as autism spectrum disorder (ASD) because it encompasses a range of developmental disorders, most familiarly an impaired ability to communicate with others and a need for repetition. There are different levels of severity and combinations of symptoms in autism. A small percentage of cases can be linked to genetic disorders, but a recent major study of twins supports earlier studies in concluding that environmental exposures during or shortly after gestation cause a majority of autism cases.22

Neurological Effects. During brain development, cells form and migrate to the cerebral cortex. In many autism cases, brain scans reveal an increased number of cells and of minicolumns of cells. Extra minicolumns and cells can affect the brainwide connectivity pattern for communication among cells, thereby altering brain function.25,26 In one recent study, autistic children had reduced connectivity between the two sides of the brain.30 In China, fetuses scheduled for abortion were scanned. Autopsies showed those exposed to sonograms longer than 10 minutes to have significant damage.55

Ultrasound Technology. Ultrasound imaging developed from sonar used to “see” objects in the ocean. An ultrasound device for fetal imaging emits short pulses of high frequency sound waves that reflect off the tissues of the fetus. The return echoes are converted into images. In addition to vibration, ultrasound waves can cause heating of the tissue and bone.15,23,27,61 Therapeutic ultrasound devices actually use these effects for healing in adults.2

Evidence. UC San Diego research reported in 2014 that key genetic markers were absent in the brains of children with autism indicating that the creation in gestation of six distinct layers with specific types of brain cells had been disrupted.56  In 2011, a major NIH (National Institute of Health) study of fraternal twins22 concluded that something in the environment during gestation or shortly afterward is causing the autism epidemic. A U.S. study found an apparent link between multiple second-trimester ultrasound exposure of girls and autism.12 Effects noted in two other research projects are low birth size9 and increased left-handedness.10 Animal studies show that ultrasound can both damage cells and alter their migration, creating the patterns observed in autistic brains.8 As long ago as 1995, a study on mice showed learning disabilities from relatively low exposure.50 Because the fetal skull is much thinner and more vulnerable to hyperthermic injury than the skull of an adult, any increase in fetal temperature can interfere with normal brain development.45,52 Low-birth-weight infants, who receive postnatal head ultrasounds in most hospitals, have 5 times the rate of autism spectrum diseases.34 For some exposure conditions, the thermal index (TI), as used in the FDA-approved output display standard, underestimates the extent of ultrasound-induced intracranial temperature increase.28

Male/Female. That more boys than girls are diagnosed with ASD could be attributed to differences in the functioning of the male and female brains with the female brain showing activity in several areas in instances when the male brain engages only one area. This could make the female brain more able to adapt to abnormal functioning. Additionally, there is post-natal research that shows the testosterone levels of prepubescent male mice greatly increased by exposure to ultrasound.62

Matching Timelines. In 1992, without testing for safety the FDA increased the allowable intensity of prenatal ultrasound 8-fold to improve images.23 Autism rates have risen dramatically since that time. As of 2012, it affected 1 in 88 U.S. children, and 1 in 54 U.S. boys, and the CDC estimate continues to increase.40 Prenatal ultrasound was once a rare medical procedure, reserved for women with high-risk pregnancies. Prenatal ultrasound is now routine for most pregnant women in developed countries. CDC reports rate of autism in 8-year-olds rose 80% in the six-year period between 2002 and 2008. The number of ultrasounds per U.S. pregnancy rose approximately 73% between the years matching the gestation times of these age groups, 1993 and 1999.29 Every year, more women have prenatal ultrasounds and have them earlier more often during a pregnancy.29 Now, the ultrasound vaginal probe, which places the acoustic beam closer to the embryo is in common use. The children of obese mothers have a higher rate of autism.41 Their abdominal fat layer often requires more of the scans to be done with the probe.42 The prevalence of autism and other neurological developmental issues continues to rise especially among the affluent.57

Ultrasound Safety. The levels set by the FDA are not based on safety studies but on relative risk.4,6,14 There is essentially no evidence that prenatal ultrasounds do not damage the fetus.3,7Researchers who have touched on the topic uniformly call for closer examination of the effects of ultrasound on the fetus.1,2,5,18 Of more concern is the high rate of defects in devices in use. A 2009 study found 40% of the hospital ultrasounds tested had malfunctioning transducers.38,39  There is widespread misunderstanding among ultrasound operators of the safety guidelines.13 Not only are there no Federal requirements for operator training, a fast-growing commercial business is keepsake ultrasound photos. Franchisers advertise that no medical background or certification is required.Ad

Call for Action

The public deserves to know immediately that there is evidence of harm.  The benefits of prenatal ultrasound are minimal in normal pregnancies. Parents electing not to have ultrasounds will not impact public health. The FDA should issue an alert.

Site Contents

Evidence includes research reports and articles. The Key Point picks out info in the document that relates to the possibility of a relationship between fetal ultrasound and autism.

Technology explains the technology of ultrasound. There are simplified explanations and links to highly technical commentaries.

Research lists studies underway as well as research needed to further the knowledge on this topic. Also included are published studies concerning brain development abnormalities at the cellular level that can be attributed to environmental causes.

Regulations come from various governmental entities in other countries. There are a few posts but no effort to cover this topic fully. However, additional information can be submitted to be included.

Overview of Alternate Hypotheses

“The Elephant in the Room” is an overview of the topic prepared by Caroline Rodgers and presented in October 2010 to the Interagency Autism Coordinating Committee of the US Department of Health and Human Services. This succinct presentation is a valuable starting place for becoming familiar with the research and hypotheses about the cause of the rise in autism and the case for investigating prenatal ultrasound as a major source.
(text of the presentation)

Key Point 48 on the Evidence page is a July 2012 presentation by Caroline Rodgers to the IACC. It examines the possibility that unintended thermal effects from ultrasound scans are causing autism.