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Research Article

Socioeconomic Inequality in the Prevalence of Autism Spectrum Disorder: Evidence from a U.S. Cross-Sectional Study

  • Maureen S. Durkin mail,

    mdurkin@wisc.edu

    Affiliations: Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America, Department of Pediatrics, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America, Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America

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  • Matthew J. Maenner,

    Affiliations: Department of Population Health Sciences, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, United States of America, Waisman Center, University of Wisconsin-Madison, Madison, Wisconsin, United States of America

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  • F. John Meaney,

    Affiliation: Department of Pediatrics, University of Arizona Health Sciences Center, Tucson, Arizona, United States of America

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  • Susan E. Levy,

    Affiliation: Department of Pediatrics, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America

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  • Carolyn DiGuiseppi,

    Affiliation: Department of Epidemiology, Colorado School of Public Health, University of Colorado Denver, Aurora, Colorado, United States of America

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  • Joyce S. Nicholas,

    Affiliation: Division of Biostatistics and Epidemiology, Departments of Neurosciences and Medicine, Medical University of South Carolina, Charleston, South Carolina, United States of America

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  • Russell S. Kirby,

    Affiliation: Department of Community and Family Health, University of South Florida, Tampa, Florida, United States of America

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  • Jennifer A. Pinto-Martin,

    Affiliation: School of Nursing and School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, United States of America

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  • Laura A. Schieve

    Affiliation: National Center on Birth Defects and Developmental Disabilities, Centers for Disease Control and Prevention, Atlanta, Georgia, United States of America

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  • Published: July 12, 2010
  • DOI: 10.1371/journal.pone.0011551

Reader Comments (2)

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Ultrasounds during pregnancy may be a substantial factor in autism

Posted by optimalpolicies on 18 Jul 2010 at 00:05 GMT

I propose that access to and use of ultrasounds during pregnancy are a substantial factor in autism. Over the past 20 years ultrasounds have become more common and more powerful. They are used more frequently (more times per person), for longer periods of time (an exam takes longer and uses ultrasound waves for longer periods of time), and the “sound” itself has more energy (for greater resolution).
Pregnant woman with high SES status share the following characteristics: (1) they have excellent health insurance that covers practically 100% of many ultrasounds; (2) they are treated by OB/GYN in private practice, usually large group practices; (3) physicians often get paid per ultrasound (more ultrasounds = more payments); (4) the large group practices are organized efficiently. Usually one physician supervises the pregnancy most of the time, but due to scheduling issues it is common for the pregnant woman to be seen by many physicians. Each physician has his/her own unique risk aversion practice, skills, and communication levels with the patient, as a result, the # of ultrasounds ordered may be determined by the physician with the greatest demand as he/she eventually sees the patient and orders more ultrasounds; (5) the large group practices in higher SES areas are arranged so that physicians rotate their on call duties to minimize the amount of time a physician is on call; as a consequence, the physician who delivers the baby is the one on call for that day, so it is unlikely to be the same as the one who follows the pregnancy; (6) I believe there is tremendous pressure on the delivering physician to minimize risk to the pregnancy and liability to the delivery doctor and the medical practice. Given the balance of risks at the time of delivery, the risks to the mother and the physician, the risks to the newborn at the time of being born (vs. the risks 3 years later, such as autism), there is tremendous pressure for better ultrasounds to minimize delivery risk. In my experience, physicians in high SES areas are very concerned about liability and insist on detailed and frequent ultrasounds.
Each of these factors exerts pressure to order more ultrasounds, more detailed ultrasounds. In addition, parents like to know the sex and sometimes other attributes of their unborn child. It is customary to share the ultrasound, real time, with the patient, as it is convenient to the patient and the technician. The other alternative, which involves less ultrasound exposure, is to print pictures or provide them electronically, and explain them later, but this approach requires more time later.
This information is based on my personal discussiones with OB/GYN physicians, conversations with staff at trade shows discussing the use and nature of ultrasounds, and my personal experience with my own kids over a period of many years. When my (yet to be born) kids have an ultrasound, I found that it is practically impossible for me to cut the duration of the exam. The technician who performs the exam and the ordering physician insist that they need detailed ultrasounds to make better medical decisions, decisions that involve less risk to the mother (and, I believe, to the physician). The physicians (many, as the pregnancy is reviewed by many doctors because OB/GYN practices in many higher-income areas consist of many physicians), insist on several ultrasounds. If the mother moves, or the baby moves or whatever, the ultrasound exposure may be longer.
I have numerous (over 50) personal contacts with many families with children with autism. These contacts are from school and group settings. I also have experience working at or with children’s medical centers in the US (in Miami, Boston) where I saw (as a student or physician) a large number of children from a wide range of socioeconomic backgrounds. I was born in a foreign country with far fewer resources than the US, at a time when ultrasounds were far less common. I noticed that the number of children with autism seems to be proportional to the number of ultrasounds of pregnant women in the US, but not in a foreign country when the parent must pay directly for the ultrasound, so that fewer ultrasounds are ordered.
Ultrasounds can disrupt cell membranes. In my laboratory we used ultrasounds to destroy cell membranes and minimize risk of infectious disease in the blood (e.g., destroy microorganisms). Even low intensity energy from ultrasounds can alter configuration or shape of molecules causing changes in brain connections and growth. These early changes are difficult to detect.
One commonly reads comparisons that radiation, such as a chest X-ray, has the same amount of radiation as travelling X hours in an airplane. However, the radiation per unit of time per molecule receiving the radiation is quite different. The energy of a lighted match may be equivalent to the energy of the sun for a number of hours. But one is more likely to get burned from touching with a finger a match than receiving equal amounts of energy from the sun over many hours over the whole body. Similarly, ultrasound energy is highly concentrated and targetted. It is not the average energy that matters, but the energy per unit of time upon a specific molecule. Depending on the location of the baby’s brain and the position of the ultrasound sender, some brain cells molecules could be exposed to multiple short doses of high intensity energy, each with a high probability of changing their configuration and signals. This matter can and ought to be studied better. Meanwhile, patients should have the smallest number of ultrasounds, for the shortest duration, consistent with clinical needs.
Eduardo Siguel, MD, PhD.
References
http://www.midwiferytoday...
Ang ES Jr, Gluncic V, Duque A, Schafer ME, Rakic P. Prenatal exposure to ultrasound waves impacts neuronal migration in mice. Proc Natl Acad Sci USA. 2006;103(34):12903–10.
http://www.nlm.nih.gov/me.... NIH position is that there are no known risks.

No competing interests declared.