New Theory Links Ultrasound to Autism
In May 2006, figures from the Centers for Disease Control (CDC) confirmed what too many parents and educators already knew: The incidence of autism is high, making it an “urgent public health issue,” according to Dr. Jose Cordero, director of the CDC’s National Center on Birth Defects and Developmental Disabilities. Only 12 years ago autism spectrum disorder (ASD) was so rare that it occurred in just one in 10,000 births.(1) Today ASD, which is characterized by a range of learning and social impairments, now occurs in one in 166 children (2)—with no sign of leveling off.
The steep increase in autism goes beyond the US: It is a global phenomenon, occurring in industrialized nations around the world. In the UK, teachers report one in 86 primary school children has special needs related to ASD.(3)
The cause of autism has been pinned on everything from “emotionally remote” mothers (since discredited) to vaccines, genetics, immunological disorders, environmental toxins and maternal infections. Today most researchers theorize that autism is caused by a complex interplay of genetics and environmental triggers. A far simpler possibility worthy of investigation is the pervasive use of prenatal ultrasound, which can cause potentially dangerous thermal effects.
Health practitioners involved in prenatal care have reason to be concerned about the use of ultrasound. Although proponents point out that ultrasound has been used in obstetrics for 50 years and early studies indicated it was safe for both mother and child, enough research has implicated it in neurodevelopmental disorders to warrant serious attention.
At a 1982 World Health Organization (WHO) meeting sponsored by the International Radiation Protection Association (IRPA) and other organizations, an international group of experts reported that “[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….”(4)
Early studies showed that subtle effects of neurological damage linked to ultrasound were implicated by an increased incidence in left-handedness in boys (a marker for brain problems when not hereditary) and speech delays.(5) Then in August 2006, Pasko Rakic, chair of Yale School of Medicine’s Department of Neurobiology, announced the results of a study in which pregnant mice underwent various durations of ultrasound.(6) The brains of the offspring showed damage consistent with that found in the brains of people with autism. The research, funded by the National Institute of Neurological Disorders and Stroke, also implicated ultrasound in neurodevelopmental problems in children, such as dyslexia, epilepsy, mental retardation and schizophrenia, and showed that damage to brain cells increased with longer exposures.(7)
Dr. Rakic’s study, which expanded on prior research with similar results in 2004 (8), is just one of many animal experiments and human studies conducted over the years indicating that prenatal ultrasound can be harmful to babies. While some questions remain unanswered, based on available information, health practitioners must seriously consider the possible consequences of both routine and diagnostic use of ultrasound, as well as electronic fetal heart monitors, which may be neither non-invasive nor safe. If pregnant women knew all the facts, would they choose to expose their unborn children to a technology that—despite its increasingly entrenched position in modern obstetrics—has little or no proven benefit?
Problems with Sound and Heat
One challenge that ultrasound operators face is keeping the transducer positioned over the part of the fetus the operator is trying to visualize. When fetuses move away from the stream of high-frequency sound waves, they may be feeling vibrations, heat or both. As the FDA warned in 2004, “ultrasound is a form of energy, and even at low levels, laboratory studies have shown it can produce physical effect in tissue, such as jarring vibrations and a rise in temperature.”(9) This is consistent with research conducted in 2001 in which an ultrasound transducer aimed directly at a miniature hydrophone placed in a woman’s uterus recorded sound “as loud as a subway train coming into the station.”(10)
A rise in temperature of fetal tissue—especially since the expectant mother cannot even feel it—might not seem alarming, but temperature increases can cause significant damage to a developing fetus’s central nervous system, according to research.(11) Across mammalian species, elevated maternal or fetal body temperatures have been shown to result in birth defects in offspring.(12) An extensive review of literature on maternal hyperthermia in a range of mammals found that “central nervous system (CNS) defects appear to be the most common consequence of hyperthermia in all species, and cell death or delay in proliferation of neuroblasts [embryonic cells that develop into nerve cells] is believed to be one major explanation for these effects.”(13)
Why should neurodevelopmental defects in rats or other mammals be of concern to expecting women? Because, as Cornell University researchers proved in 2001, brain development proceeds in the same manner “across many mammalian species, including human infants.”(14) The team found “95 neural developmental milestones” that helped them pinpoint the sequence of brain growth events in different species.(15) Therefore, if repeated experiments show that elevated heat caused by ultrasound damages fetal brains in rats and other mammals, one can logically assume that it can harm human brains, too.
In fact, the FDA and professional medical associations know that prenatal ultrasound can be dangerous to humans, which is why they have consistently warned against the non-medical or “keepsake” ultrasound portrait studios that have cropped up in malls throughout the country.(16)
Read Full Article: Midwifery Today
- “National Autism Treatment Plan for Excellence in IDEA” Petition to the President of the United States. www.petitiononline.com/natpidea/petition.html. Accessed 23 Sep 2006.
- “How Common Are Autism Spectrum Disorders (ASD)?” Centers for Disease Control and Prevention. www.cdc.gov/ncbddd/autism/asd_common.htm. Accessed 23 Sep 2006.
- “Autism in schools: Crisis or challenge?” The National Autistic Society. www.nas.org.uk/nas/jsp/polopoly.jsp?d=160&a=3464. Accessed 23 Sep 2006.
- “International Programme on Chemical Safety. Environmental Health Criteria 22. Ultrasound.” 1982. United Nations Environment Programme, International Labour Organisation and International Radiation Protection Association. www.inchem.org/documents/ehc/ehc/ehc22.htm. Accessed 22 May 2006.
- Keiler, H., et al. 2001. Sinistrality—a side-effect of prenatal sonography: A comparative study of young men. Epidemiology 12(6): 618–23; Campbell, J.D., et al. 1993. Case-controlled study of prenatal ultrasonography exposure in children with delayed speech. Can Med Assoc J 149: 10, 1435–40.
- “Ultrasound Can Affect Brain Development.” Truth Out Issues. www.truthout.org/issues_06/080806HA.shtml. Accessed 25 Sep 2006.
- Ang, E.S., Jr., et al. 2006. Prenatal exposure to ultrasound waves impacts neuronal migration in mice. PNAS 103(34): 12903–10. www.pnas.org/cgi/content/abstract/103/34/12903?maxtoshow. Accessed 11 Aug 2006.
- Rados, Carol. 2004. FDA Cautions Against Ultrasound “Keepsake” Images. FDA Consumer Magazine. www.fda.gov/fdac/features/2004/104_images.html. Accessed 11 Sep 2005.
- Samuel, Eugenie. 2001. Fetuses can hear ultrasound examinations. New Scientist. www.newscientist.com/article/dn1639-fetuses-can-hear-ultrasound-examinations-.html. Accessed 11 May 2006.
- Miller, M.W., et al. 2002. Hyperthermic teratogenicity, thermal dose and diagnostic ultrasound during pregnancy: implications of new standards on tissue heating. Int J Hyperthermia 18(5): 361–84.
- Graham, Jr., M., M.J. Edwards and M.J. Edwards. 1998. Teratogen Update: Gestational Effects of Maternal Hyperthermia Due to Febrile Illnesses and Resultant Patterns of Defects in Humans. Teratology 58: 209–21.
- Clancy, B., R.B. Darlington and B.L. Finlay. 2001. Translating developmental time across mammalian species. Neuroscience 105(1): 7–17.
- See note 9 above.