Posts
Found on the Midwifery Today website
by Lydi Owen© 2008 Midwifery Today, Inc. All rights reserved.
[Editor's note: This article first appeared in Midwifery Today Issue 86, Summer 2008.]
There is a rule of labor that forbids a woman to push with contractions until her cervix is completely dilated to 10 cm. Women are warned that to push before this doorway is completely open and out of the way will result in a swollen and/or torn cervix.
What will supposedly happen if the cervix swells?
Doctors, nurses, midwives, doulas and childbirth educators all warn that a swollen cervix will impede labor and increase the chances of tearing the cervix, thus causing hemorrhage. They have been taught that a swollen cervix is easily broken or pulverized. If this is indeed the truth, then why do most women during labor have an irresistible urge to begin bearing down before dilation is complete?
Could it be that the instinctual wisdom of our bodies has become our enemy? Is Spirit trying to destroy us instead of guiding us? Why would we feel the need to begin bearing down at 5–6 cm (or sooner) if it would shatter the gateway to the baby’s outer world?
These were questions that I pondered as a midwife, as I watched woman after woman give birth in the 1970s. Each of us struggled through the phase of labor when we wanted to push, but we knew that we had to refrain from doing so because that was what we had been taught in childbirth education classes. We had learned this from previous births in the hospital.
By what authority should we doubt the information given to us by the learned men and women of science?
Collectively, women decided that remaining passive during labor was better than risking injury or death of themselves and/or their unborn babies by obeying “outdated” promptings of their bodies, whose wisdom hadn’t kept up with science.
Could professionals be mistaken about when women can begin bearing down during labor, because they forgot one simple part of the equation—that of observing non-medicated women in labor in their natural habitats?
Remember this: People at one time believed that the world was flat. Dr. Ignaz Semmelweiss was ridiculed until his death in 1865 for suggesting that germs were responsible for the widespread child bed fever that killed an epidemic number of women simply because doctors didn’t wash their hands.(1)
How did this “Rule of Ten” come about?
In 1951 doctors Greenhill and DeLee wrote “During the first stage of labor no abdominal pushing is allowed because the cervix will tear.”(2)
We can safely assume that the women being studied by Greenhill and DeLee were under the influence of drugs, because in the mid-20th century the orgy of drug interference during labor and birth was at its height of glory. Almost no women were informed enough to withstand the onslaught of drugs given to them during birth in the hospital. Unfortunately, the situation has not changed in the sixty years since.
Therefore, these doctors were scientifically incorrect in concluding that the “Rule of Ten” was valid, without simultaneously observing a control group of drug-free laboring women in the upright position (as opposed to being drugged and lying down in beds).
The only place that they would have been able to make these observations by comparison would have been at homebirths. In the 1950s, homebirths were almost non-existent.
In the early part of the 1970s many American women, tired of being dominated by wrong medical thinking, left the system and went home to birth their children. I was one of these women. That birth led to my becoming a midwife.
The first time I witnessed the cervix miraculously responding to being pushed on at 6 cm dilation was when a woman was giving birth to her third baby. Susan had a quick and easy labor. When she reached 6 cm, she could not hold back from pushing. Her body gave her clear signals that it was time for her to aid the uterus in the expulsion of her unborn child, himself pushing to be born. She began to grunt and bear down involuntarily, making primitive animal sounds that emanated from deep inside her throat.
I, supposedly the learned one, watched her break the cardinal rule in obstetrics. Aloud, I recited, “You must not push. You’re not fully dilated. You can tear or injure your cervix. Pant like a puppy!”
She obeyed with difficulty.
After thirty minutes of this ridiculous scenario, I checked her dilation again, hoping that she would now be dilated to 10 cm so that I could release her from her agony by giving her “permission” to push. Horror upon horrors greeted my fingers as I discovered that she was still only 6 cm, but now her cervix was swollen from not pushing.
She had several more contractions while I was on the telephone (I was new at midwifery), frantically calling midwives in another state because there weren’t any in Las Vegas, for advice on what to do about this “problem.” The midwife I spoke to wasn’t any more experienced than I was and apologized for not knowing what to tell me.
While I was on the phone, Susan, tired of panting like the puppy she wasn’t, finally just went ahead and began pushing without my “permission.” I threw down the telephone, rushed over and quickly slipped on a sterile glove. As she pushed, I felt her very puffy cervix, now 7 cm, slip over the baby’s head. Out popped his little head, all in one contraction.
Her cervix didn’t tear, the swelling subsided immediately, and mother and baby were both fine. Mom was no doubt relieved that she had survived her well-meaning, but ignorant, midwife.
I went home thinking about that one, convinced that we were just lucky that everything turned out okay in spite of the fact that this woman ignored science in favor of primal wisdom.
The next time I encountered a “defiant” woman was soon after, when another woman went into labor. Carol was expecting her second baby. During active labor, at 4 cm—when her cervix was soft and stretchy—Carol squatted by her bedroom door and hung onto the doorknob with both hands. She then began to bear down with each very strong contraction.
“Oh, great, here we go again,” I thought as I advised her to desist from pushing.
Carol was less “obedient” than Susan had been and didn’t give ear to my dire warning. She just grunted and pushed like an empowered woman, completely unafraid, and within 30 minutes dilated to 10 cm.
Her baby was fine, her cervix was fine, and this time I was fine. I now understood the power of fearless women and the primal (of first importance) wisdom of our bodies.
As I attended more and more births, I learned that women could safely push during labor sooner than what the textbooks claimed. However, the question wasn’t whether a woman pushed, but how and when.
In my quest to “help” the next woman in labor with my newly discovered information, I wrongly decided to “assist” her to dilate faster by massaging and stretching her cervix when she was 4 cm dilated. What I didn’t yet understand was that the cervix has to be thin, soft and stretchy for this to work and the woman has to be getting the signal to bear down of her own accord, not my good intentions to help her get labor over with faster.
I ended up sending her into the hospital for “failure to progress,” when I caused the failure to progress. I was embarrassed that I had prevented her from having a good homebirth just because I was ignorant. I came to realize that I had much to learn about the different stages of labor from observation of women in their natural habitats. What we have been taught about labor and birth in medical textbooks comes from observation of medicated women in “laboratories” (hospitals), like mice in cages. Observations of women lying in beds, laboring under the influence of analgesics and anesthetics provide no real clue to the workings of the human body during labor and birth.
For decades women had been drugged during labor and put to sleep during the actual birth of the baby, so I can certainly understand how the “Rule of Ten” must have come about. If a woman was not dilated completely before the hands of the strong male doctor forcefully pushed, pulled and tugged the sedated infant out of a limp body, then certainly the doctor could easily have torn her cervix with his brute strength if it wasn’t completely out of the way (dilated to 10 cm). Gladys McGarey, MD, writes in the Women’s Wellness section of Venture Inward’s November/December 2007 issue, “Let’s respect nature’s wisdom…. Our job is to recognize and support the Divine order of things.”(3)
Dr. McGarey writes about the conditions of women in Afghanistan in 2005 as they gave birth to their babies. The attendants didn’t understand the anatomy and physiology of labor and birth and therefore used severe external pressure to deliver the babies. She also writes that this caused problems such as ruptured uteri and bladders, leading to many maternal deaths.
In the US, in the early part of the 20th century, the “Rule of Ten” no doubt came about for that same reason. Six to nine of every 1000 women died in childbirth in the early part of the 20th century.(4) If the cervix is not out of the way when severe fundal pressure is used, it will act as a counter-force to external fundal pressure and will inevitably result in either a torn cervix or uterus.
I have attended the labors and births of many, many Hispanic women. I have observed many friends and family members of the laboring women who do not have any medical or anatomical knowledge of the human body attempt to speed up labor in these same very unwise ways. I was attending a laboring woman who was pregnant with her first child. She was handling the contractions like a pro, but the labor was slow, which is normal for a first time mother.
Veronica preferred to walk during the contractions. Her cervix stayed at 4 cm for several hours (a normal occurrence), but now her cervix was beginning to soften from the repeated contractions. However, Veronica’s mother was getting impatient. As I had done in the past, she figured she would help her daughter get this labor over with more quickly. From the grandmother’s point of view, she was going to help get that big baby out of that small vaginal opening.
I had gone into the kitchen to get a drink of water when I heard Veronica let out an anguished moan from the bedroom. Alarmed, I rushed into the bedroom to find out what was wrong. Veronica sounded like she was in serious pain. I discovered that her mother was standing behind her with both her arms wrapped around her daughter’s abdomen, pressing down as hard as she could on the top of Veronica’s belly during a contraction.
Her mother believed that she was helping her daughter, but to me the way she was pushing on her stomach looked barbaric. The grandmother did not understand that there was another doorway (the cervix) inside her daughter’s body that had to open before the baby could be born through the exterior doorway—the vaginal opening. In her simple, uneducated mind, she thought she was helping. She did not know that she might tear the cervix by what she was doing because she didn’t even know that there was such a thing as the cervix in the way. I knew better than to insult this grandmother by telling her to stop doing that, so I just made eye contact with Veronica and motioned with my eyes that she come into the other bedroom. Veronica kindly removed her mother’s hands from her belly and followed me, telling her mother in Spanish that I was going to examine her.
Her mother was furious that she was unable to help her daughter the way she had been taught in the small farm town in Mexico where she was born. She clearly considered me an ignorant intruder. However, what she had been doing was dangerous. I wondered how many women and babies had actually died from uterine ruptures in Mexico during labor and birth because of attendants who unwittingly pushed on a mother’s uterus to “help” her, the same way they do in Afghanistan and did in the US in the past.
Midwifery in itself isn’t dangerous. Midwifery without proper education can be dangerous in the face of aggressive caregivers. Certainly we all need an understanding of anatomy and physiology to be effective midwives.
However, rather than accepting the “Rule of Ten” just because it is written in a medical textbook, we must question whether this rule is valid and examine how it came about, especially as we observe multitudes of women wanting to push before they are completely dilated. For over a century, women in the US have been conditioned to think that doctors are the experts. As a result, we have buried our primal instincts somewhere deep inside our subconscious minds. Just telling a laboring woman that she can trust her body won’t wipe away centuries of conditioning that it isn’t okay to do so without scientific proof. Unless a woman has been raised on an island far from civilization, she will likely have read or heard something that influences how she will give birth. Everything she has learned has the risk of interfering with or empowering her to listen to and respond to her primal instincts during birth.
I believe that the scientific evidence for eliminating the “Rule of Ten” comes from page 171 of Helen Varney’s Nurse Midwifery, where she describes what happens in the phase of maximum slope.(5)
First let me say that a non medicated woman will never push so hard against her undilated cervix that it tears, because it will hurt. Pain is a natural deterrent to pushing too hard. However, when done in the correct manner, pushing to help rotate a baby and dilate oneself will actually eliminate a great deal of pain and cut hours off one’s labor and birth.
Women feel greatly empowered when they can merge with their contractions, unafraid, because the pain diminishes as they do so and labor time is significantly reduced.
Stages of LaborAll textbooks define normal labor and birth as occurring in three stages: First stage is considered to be from the start of active labor until complete dilation; second stage is the birth of the baby or the pushing stage; third stage is the birth of the placenta.
The first stage of labor is further subdivided into the latent phase and the active phase. The active phase is then further subdivided into three more phases: the acceleration phase, the phase of maximum descent and the deceleration phase, also known as transition.
Yet, the same breathing technique is advocated for all the subdivisions of active phase and the
“Rule of Ten” is adhered to no matter what.
How much sense does that make? It’s like asking a woman sweeping the floor to breathe the same way that a woman running a marathon would do, or like asking a man digging a ditch with a shovel to breathe and blow instead of grunting as he throws a load of dirt over his shoulder.
I have frequently stated that most of the birthing women I have observed wish to begin pushing, bearing down or grunting at 5–6 cm. This is because they have entered the phase of maximum slope.
According to Varney, three sequential phases of active labor were defined and described by Dr. E.A. Friedman in 1978 in Labor: Clinical Evaluation and Management.(6) She states: “The phase of maximum slope is the time when cervical dilatation is occurring most rapidly from 3–4 cm to about 8 cm.”(7)
This dilation averages 3 cm per hour in nulliparas. In multiparas, it averages 5.7 cm per hour. The average maximum rate of descent in first-time mothers is 1.6 cm per hour and in multips it is 5.4 cm per hour.
This means that for both primips and multips, doctors observed that women dilated rapidly from 4–8 cm in approximately one hour or so. The descent of the baby’s head in first-time mothers was naturally slower than for women who had already given birth to other children vaginally. Can you imagine the descent and dilation that occurs in women who give birth at home, who are walking during labor and who are not medicated? Can you understand now why the rule needs to change?
The phase of maximum slope is defined as dilation occurring most rapidly from 4–8 cm dilation, but my experience shows that it occurs most rapidly between 5 and 8 cm.
I believe that a Divine reason is behind the fact that the cervix stays at 4 cm for the majority of labor.
Each contraction starts in the top part of the uterus and spreads downward; it is stronger and persists longer in the upper region. On reaching the lower uterine segment the contraction weakens considerably, permitting the cervix to dilate. There is neuromuscular harmony between the upper and lower segment throughout labor. The muscular fibers of the upper segment contract strongly and retract (become progressively shorter), while the fibers of the lower segment contract only slightly and dilate. As the upper segment contracts and retracts, the lower uterine segment has to “thin out” to accommodate the descending baby. This continues until the cervix if fully dilated and the baby can leave the uterus.
The upper segment increases in thickness up to four times, diminishing the uterine cavity considerably where the baby is lying.(8) As this is happening, the lower segment becomes more and more yielding to the pressure of the baby’s head against it. This is why at 5 cm, the cervix is usually so stretchy and thin that it can no longer hold back the flexing, rotating and descending baby.
Because of Divine design, as the uterine cavity itself diminishes in size due to the increased thickness of the upper segment and the increased thinness of the lower segment, the baby is protected from strangling on the cord because his position relative to the cord and placenta does not change as he drops farther and farther into the pelvis. Many babies get wrapped in their cords before birth. If this decrease in size of the uterine cavity didn’t take place, the baby could easily strangle in the umbilical cord during labor and birth.
When the baby has reached its maximum descent before complete dilation (8 cm), the mother enters the deceleration phase. This phase is the end of the active phase. Dilation now temporarily slows. At this point, many mothers wish to lie down and rest, or get onto hands and knees to complete dilation. Many mothers I have observed have to rest for only a few minutes before the cervix relaxes and the mother feels like pushing again. The cervix can no longer withstand the pressure of both the baby and the mother’s pushing efforts and relinquishes its hold on the baby.
In summary, after decades of believing the “Rule of Ten” to be gospel truth, many women have difficulty letting go of false beliefs. We will take a while before we again trust our primal wisdom. However, when we do, I truly believe that the cesarean rate will drop dramatically.
One of the main reasons for cesareans is because of slow labor; yet labor is often slow because of the rules we have made.
Lydi Owen is the mother of six, grandmother of six (another on the way) and great-grandmother of four. She has practiced midwifery for 36 years and helped over 2600 babies into the world. She has written three books, produced a DVD and is founder of the nonprofit Association for the Prevention of Maternal Attachment Disorders. Her Web site is www.powerbirth.com.
References:
1. www.cdc.gov/ncidod/EID/vol7no2/cover.htm. Accessed 13 Feb 2008.
2. Greenhill, J.P., and J. DeLee. 1951. The Principles and Practice of Obstetrics, 10th ed. Philadelphia: WB Saunders.
3. McGarey, G. 2007. Venture Inward. Virginia Beach, Virginia: Association for Research and Enlightenment, Inc., November/December.
4. “Achievements in Public Health, 1900–1999: Healthier Mothers and Babies,” MMWR, 1 Oct 1999.
5. Varney, H. 1980. Nurse Midwifery. Boston: Blackwell Scientific Publications.
6. Friedman, E.A. 1955. Primipara Labor Curve. Obstet Gynecol 6: 569. Cited in Varney, p. 170.
7. Varney, p. 171.
8. Buhimschi, C.S., et al. Myometrial thickness during human labor and immediately post partum. Am J Obstet Gynecol 188: 553–59; Myles, M. 1981. Textbook for Midwives, 9th ed. New York: Churchill Livingstone.
Showing posts with label midwifery today. Show all posts
Showing posts with label midwifery today. Show all posts
Tuesday, February 23, 2010
Wednesday, September 23, 2009
Wednesday, July 29, 2009
Questions about Prenatal Ultrasound and the Alarming Increase in Autism
Written by Caroline Rodgers for Midwifery Today Issue 80
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)
The risks to the baby are potentially higher in commercial enterprises due to the higher acoustic output required for high-definition images, a potentially long session—as technicians hunt for suitable images—and the employment of ultrasound operators who may have no medical background or appropriate training. These variables, along with factors such as cavitation (a bubbling effect caused by ultrasound that can damage cells) and on-screen safety indicators that may be inaccurate by a factor ranging from 2–6 (17), make the impact of ultrasound uncertain even in expert hands. Quite simply, if ultrasound can injure babies, it can cause the same damage whether done for routine, diagnostic or "entertainment" purposes.
Elevated Maternal Temperatures Cause Birth Defects
Understanding what happens when the fetus's temperature increases, whether caused by an elevation in maternal core temperature or by the more local effect of ultrasound, is the key to appreciating prenatal ultrasound risks. An individual's body temperature varies throughout the day due to various factors such as circadian rhythms, hormone fluctuations and physical exertion. While people may have up to 1.5° F in each direction of what is considered a "normal" core temperature, the overall average among people is 98.6° F. An increase of only 1.4° F to 100° F can cause headaches, body aches and fatigue, enough to get the individual excused from work. A temperature of 107 F can cause brain damage or death.
A core temperature of about 98.6° F is important because that is the point at which many important enzyme reactions occur. Temperature affects the actual shape of the proteins that create enzymes, and improperly shaped proteins are unable to do their jobs correctly. As factors such as the amount of heat or duration of exposure increase, enzyme reactions become less efficient until they are permanently inactivated, unable to function correctly even if the temperature returns to normal.(18)
Because temperature is critical to proper enzyme reactions, the body has built-in methods to regulate its core temperature. For instance, when it is too low, shivering warms it up; when it is too high, sweating wicks off the heat. For obvious reasons, fetuses cannot cool off by sweating. However, they have another defense against temperature increases: Each cell contains something called heat shock (HS) proteins that temporarily stop the formation of enzymes when temperatures reach dangerously high levels.(19)
Complicating the issue is the fact that ultrasound heats bone at a different rate than muscle, soft tissue or amniotic fluid.(20) Further, as bones calcify, they absorb and retain more heat. During the third trimester, the baby's skull can heat up 50 times faster than its surrounding tissue (21), subjecting parts of the brain that are close to the skull to secondary heat that can continue after the ultrasound exam has concluded.
Elevated temperatures that might only temporarily affect the mother can have devastating effects on a developing embryo. A 1998 article in the medical journal Cell Stress & Chaperones reported that "the HS response is inducible in early embryonic life but it fails to protect embryos against damage at certain stages of development." The authors noted, "With activation of the HS response, normal protein synthesis is suspended…but survival is achieved at the expense of normal development."(22)
Autism, Genetics and Twin Studies
What does elevated body temperature have to do with autism? Geneticists are trying to crack the DNA mysteries behind ASD. Recently researchers linked two mutations of the same X chromosome gene to autism in two unrelated families, although they do not yet understand at what stage these genes were damaged.(23) Because sibling and twin studies show a higher prevalence of autism among children in families with one autistic child, geneticists expected to find inherited factors, but despite millions of dollars invested in the search, no clear explanation indicates that ASD is inherited. Perhaps scientists need look no further than at the thermal effects of ultrasound for many answers.
If prenatal ultrasound is responsible for some cases of autism, it stands to reason that if one twin were autistic, the other would have a high probability of being affected, since both would have been exposed to ultrasound at the same time. In both identical and fraternal twins, one twin could be more severely affected than the other if he or she happened to take the brunt of the heat or sound waves. In the case of fraternal twins, since autism strikes males between three to five times more often than females, the sex of the twins also could make a difference in outcome.
A 2002 study showed that simply being a twin substantially increased the likelihood of autism, making twinning a risk factor.(24) Could this increased twin risk factor have to do with the practice of giving mothers with multiple gestations more ultrasounds than those expecting single births? While not discounting the role genetics may play in autism, the possible impact of prenatal ultrasound deserves serious consideration.
Ultrasound Warnings Unheeded
The idea that a prenatal ultrasound can be hazardous is not new. The previously mentioned 1982 WHO report, in its summary "Effects of Ultrasound on Biological Systems," stated that "…animal studies suggest that neurological, behavioral, developmental, immunological, haematological changes and reduced fetal weight can result from exposure to ultrasound."(25)
Two years later, when the National Institutes of Health (NIH) held a conference assessing ultrasound risks, it reported that when birth defects occurred, the acoustic output was usually high enough to cause considerable heat.(26). Although the NIH has since stated that the report "is no longer viewed…as guidance for current medical practice," the facts remain unchanged.
Despite the findings of these two major scientific gatherings, in 1993 the FDA approved an eight-fold increase in the potential acoustical output of ultrasound equipment (27), greatly increasing the possibility of disastrous pregnancy outcomes caused by overheating. Can the fact that this increase in potential thermal effects happened during the same period of time the incidence of autism increased nearly 60-fold be merely coincidental?
Hot Tubs, Steam Rooms, Saunas and Maternal Fevers
If the culprit is heat, then what about other situations in which heat impacts pregnancy? A 2003 study titled, "A report of heat on embryos and fetuses" in the International Journal of Hyperthermia states, "hyperthermia during pregnancy can cause embryonic death, abortion, growth retardation and developmental defects."(28) It further states, "An elevation of maternal body temperature by 2 degrees Centigrade [3.6 degrees Fahrenheit] for at least 24 hours during fever can cause a range of developmental defects."(29) The report noted that necessary data to draw conclusions on exposure times less than 24 hours were lacking (30), leaving open the possibility that elevated maternal temperatures for shorter periods may adversely affect fetuses.
A study reported in the Journal of the American Medical Association (JAMA) found that "women who used hot tubs or saunas during early pregnancy face up to triple the risk of bearing babies with spina bifida or brain defects."(31). Hot tubs and baths present greater dangers than other heat therapies such as saunas and steam rooms because the immersion in water foils the body's attempt to cool off via perspiration, in much the same way fetuses cannot escape elevated temperatures in the womb.
All of this taken together establishes the fact that heat, whether caused by elevated maternal temperature or by an ultrasound transducer that remained over one area too long, can set into motion damaging changes in a developing baby. Using common sense, why would anyone think that intruding upon the continuous, seamless development of the fetus, which has for millions of years completed its work without assistance, be without consequences?
Vaccine and Thimerosal Controversy
Despite long-standing evidence that ultrasound induces thermal effects and that thermal effects can harm fetal brain development, the cause of autism has remained so elusive to researchers that many autism societies use a puzzle piece as part of their logos. Particularly confounding is the fact that ASD plagues the children of high-income, well-educated families who have the best obstetrical care money can buy. Why would women who took their prenatal vitamins, observed healthy diets, refrained from smoking or drinking and attended all regularly scheduled prenatal visits bear children with profound neurologically based problems?
Some believe that childhood vaccines, at first available only to those who could afford them, cause autism. Many vaccines contained thimerosal, a mercury-based preservative, which was thought to have a cumulative neurotoxic effect on children, especially as the number of childhood vaccines increased during the same period of years that the prevalence of autism increased. However, after an exhaustive review in 1999, the FDA found no evidence of harm in the use of thimerosal in childhood vaccines.(32)
Despite those findings, that same year the FDA, NIH, CDC, Health Resources and Services Administration (HRSA) and American Academy of Pediatrics (AAP) together urged vaccine manufacturers to reduce or eliminate thimerosal in childhood vaccines.(33) Pharmaceutical companies complied, and ultimately reduced the infant thimerosal exposure by 98%.(34)
Interestingly, not only did autism rates fail to decrease, they continued to increase. ASD increases are between 10 to 17 percent every year, according to the Autism Society of America (35), indicating that thimerosal is not to blame.
Thimerosal was not the only area of concern in the vaccine-autism controversy. Many people believed that a correlation existed between the triple vaccine MMR (mumps, measles and rubella) and ASD. However, a large, retrospective epidemiological study of more than 30,000 children in Japan between 1988 and 1996 found that the autism rate continued to climb after the vaccine was withdrawn.(36) Those results were no different than the outcome of a 1999 study published in The Lancet, that showed no corresponding jump in autism in the UK after the introduction of the MMR vaccine.(37)
A 2001 study published in JAMA examining California autism and MMR vaccination rates said the results did "not suggest an association between MMR immunization among young people and an increase in autism occurrence."(38) While concerns about vaccines and mercury exposure should not be dismissed, evidence to date does not implicate either one as a major factor in the explosion of ASD cases.
Global Autism Epidemic
Statistics on the increase of autism worldwide among industrialized nations show that it has emerged in just the last few decades across vastly different environments and cultures. What do countries and regions with climates, diets and exposure to known toxins as disparate as the US, Japan, Scandinavia, Australia, India and the UK have in common? No common factor in the water, air, local pesticides, diet or even building materials and clothing can explain the emergence and relentless increase in this serious, life-long neurodevelopmental disorder.
What all industrial countries do have in common is the quiet yet pervasive change in obstetrical care: All of them use routine prenatal ultrasound on pregnant women.
In countries with nationalized healthcare, where virtually all pregnant women are exposed to ultrasound, the autism rates are even higher than in the US, where due to disparities in income and health insurance, some 30 percent of pregnant women do not yet undergo ultrasound scanning.
The Changes in Ultrasound
In considering initial studies indicating that prenatal ultrasound is safe, one must factor in the ways in which the technology and its applications have continually changed and how that has altered the potential exposure of unborn children. Besides the huge increase in allowable acoustic output in the early 1990s, the following changes have made the field of prenatal ultrasound riskier than ever:
* The number of ultrasound scans conducted during each pregnancy has increased, with women often receiving two or more scans even in low-risk situations.(39) Women in "high-risk" situations may receive many more scans—which, ironically, may raise their risk.
* The range of time within an embryo or fetus's development when ultrasound is performed has extended to very early in the first trimester and continues into the third trimester, right up to delivery. Fetal heart monitors that are used prior to delivery—sometimes for hours—have not been shown to reduce neurological problems and may increase them.(40)
* The development of the vaginal probe, which positions the beam of sound much closer to the embryo or fetus, may put it at higher risk.
* The use of Doppler ultrasound, which is used to study blood flow or to monitor the baby's heartbeat, has increased. According to the 2006 Cochrane Database of Systematic Reviews, "routine Doppler ultrasound in pregnancy does not have health benefits for women or babies and may do some harm."(41)
Increasingly Common Birth Defects
Dr. Rakic's research team, cited earlier in this article for its recent study on mouse brains and ultrasound, pointed out that "the probe was held stationary for up to 35 minutes, meaning that essentially the entire fetal mouse brain would have been continually exposed to the ultrasound for 35 minutes…in sharp contrast to the duration and volume of the human fetal brain exposed by ultrasound which will typically not linger on a given tissue volume for greater than one minute."(42) This is an excellent point, which is worth pursuing.
One of the most popular non-medical uses of ultrasound, which can extend a medically indicated session, is to determine the sex of the baby.
# Could this have a connection to the increase in birth defects involving the genitals and urinary tract?
The March of Dimes says that these types of birth defects affect "as many as 1 in 10 babies," adding that "specific causes of most of these conditions is unknown."(43)
Following this line of thought, consider what other parts of the body are scrutinized by ultrasound technicians, such as the heart, where serious defects have soared nearly 250 percent between 1989 and 1996.(44) The list of unexplained birth defects is not a short one, and in light of what is emerging about prenatal ultrasound, scientists should take another look at all recent trends, as well as the baffling 30% increase in premature births since 1981, now affecting one in every eight children (45), with many showing subsequent neurological damage.(46)
Although many claim that ultrasound benefits outweigh the risks, that statement has no basis and much evidence is to the contrary. A large randomized trial of 15,151 pregnant women, conducted by the RADIUS Study Group, found that in low-risk cases, high-risk subgroups and even in cases of multiple gestations or major anomalies, the use of ultrasound did not result in improved outcome in the pregnancies.(47) The argument that ultrasound is either reassuring to the parents or provides an early opportunity for bonding pales in the face of the possible risks that are emerging as new data become available. Parents and health practitioners may not be able to easily turn away from this window on the womb and resume more traditional practices in obstetrics and midwifery. However, with the disturbing trend in autism and other equally troubling, unexplained birth-related trends, it does not make sense to blindly employ a technology that is not reliably safe for unborn babies.
Caroline Rodgers
Editor's Note: Read more about ultrasound on our Web site:
* Ultrasound: Weighing the Propaganda Against the Facts - by Beverley Lawrence Beech
* Ultrasound: More Harm than Good? - by Marsden Wagner
* Search more about ultrasound.
References:
1. "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.
2. "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.
3. "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.
4. "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.
5. 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.
6. "Ultrasound Can Affect Brain Development." Truth Out Issues. www.truthout.org/issues_06/080806HA.shtml. Accessed 25 Sep 2006.
7. Ibid.
8. 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.
9. 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.
10. 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.
11. 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.
12. Ibid.
13. 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.
14. Clancy, B., R.B. Darlington and B.L. Finlay. 2001. Translating developmental time across mammalian species. Neuroscience 105(1): 7–17.
15. Ibid.
16. See note 9 above.
17. See note 13 above.
18. Wilson, D.E. 2004. "Body Function Dependent On Body Temperature." In Wilson's Temperature Syndrome—A Reversible Low Temperature Problem. eBook. www.wilsonsthyroidsyndrome.com/eBook/Chapters/02Temp.cfm. Accessed 19 Sep 2006.
19. "How enzymes work." Biotopics. www.biotopics.co.uk/other/enzyme.html. Accessed 19 Sep 2006.
20. "The ultrasound procedure: Physical effects and research." Birth. www.birth.com.au/class.asp?class=6610&page=5. Accessed 23 Sept 2006.
21. Barnett, S.B. "Can diagnostic ultrasound heat tissue and cause biological effects?" In S.B. Barnett and G. Kossoff, eds. 1998. Safety of Diagnostic Ultrasound. Carnforth, UK: Parthenon Publishing.
22. Edwards, M.J. 1998. Apoptosis, the heat shock response, hyperthermia, birth defects, disease and cancer. Where are the common links? Cell Stress Chaperones 3(4): 213–20.
23. Klauck, S.M., et al. 2006. Mutations in the ribosomal protein gene RPL10 suggest a novel modulating disease mechanism for autism. Mol Psychiatry. advance online publication 29 August 2006. doi:10.1038/sj.mp.4001883.
24. Betancur, C., M. Leboyer and C. Gillberg. 2002. Increased Rate of Twins among Affected Sibling Pairs with Autism. Am J Hum Genet 70: 1381–83.
25. See note 4 above.
26. "Diagnostic Ultrasound Imaging in Pregnancy." National Institutes of Health Consensus Statement Online. 5(1): 1–16.
27. See note 16 above.
28. Edwards, M.J., R.D. Saunders and K. Shiota. 2003. Effects of heat on embryos and foetuses. Int J Hyperthermia. 19 (3): 295–324.
29. Ibid.
30. Ibid.
31. Milunsky, A., et al. 1992. Maternal heat exposure and neural tube defects. JAMA 268(7): 882–85.
32. "Thimerosal in Vaccines." U.S. Food and Drug Administration. www.fda.gov/cber/vaccine/thimerosal.htm. Accessed 21 Sep 2006.
33. Ibid.
34. "Thimerosal and Vaccines." Centers for Disease Control. www.cdc.gov/nip/vacsafe/concerns/thimerosal/faqs-thimerosal.htm#3. Accessed 27 Sep 2006.
35. "Facts and Statistics." Autism Society of America. www.autism-society.org/site/PageServer?pagename=FactsStats. Accessed 21 Sep 2006.
36. Honda, H., Y. Shimizu and M. Rutter. 2005. No effect of MMR withdrawal on the incidence of autism: a total population study. J Child Psychol Psychiatry 46(6): 572–79.
37. Taylor, B, et al. 1999. Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet 353(9169): 2026–29.
38. Dales, L., S.J. Hammer and N.J. Smith. 2001. Time Trends in Autism and in MMR Immunization Coverage in California. JAMA 285(22): 1183–85.
39. Stephens, M.B. 2000. American Family Physician Conference Highlights: Majority of Pregnant Women Want Prenatal Ultrasound. Am Fam Physician (62)12: 2665.
40. Wagner, M., and M.G. Wagner. 1994. Pursuing the Birth Machine, 1st ed. French's Forest, Australia: James Bennett Pty Ltd.
41. Bricker, L., and J.P. Neilson. 2006. "Routine Doppler ultrasound in pregnancy." The Cochrane Collaboration 3. www.cochrane.org/reviews/en/ab001450.html. Accessed 23 Sep 2006.
42. Smith, M. 2006. "Ultrasound Affects Development of Murine Brains." Medpage Today. www.medpagetoday.com/Radiology/GeneralRadiology/tb/3882. Accessed 13 Aug 2006.
43. "Genital and Urinary Tract Defects." March of Dimes. www.marchofdimes.com/printableArticles/4439_1215.asp. Accessed 27 Aug 2006.
44. "Healthy from the Start." 1999. The Pew Charitable Trusts (Environmental Health Commission). www.pewtrusts.com/pdf/hhs_healthy_from_start.pdf. Accessed 25 Sep 2006.
45. Behrman, R.E., and A.B. Stith, eds. 2006. Preterm Birth: Causes, Consequences, and Prevention. Washington, D.C.: National Academies Press. http://newton.nap.edu/catalog/11622.html. Accessed 20 Sep 2006.
46. "New research offers clues to prevent brain damage in premature babies." 2006. Medical News Today. www.medicalnewstoday.com/medicalnews.php?newsid=28786. Accessed 25 Sep 2006.
47. Ewigman, B.G., et al. 1993. Effect of Prenatal Ultrasound Screening on Perinatal Outcome. N Engl J Med 329(12):821–27.
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)
The risks to the baby are potentially higher in commercial enterprises due to the higher acoustic output required for high-definition images, a potentially long session—as technicians hunt for suitable images—and the employment of ultrasound operators who may have no medical background or appropriate training. These variables, along with factors such as cavitation (a bubbling effect caused by ultrasound that can damage cells) and on-screen safety indicators that may be inaccurate by a factor ranging from 2–6 (17), make the impact of ultrasound uncertain even in expert hands. Quite simply, if ultrasound can injure babies, it can cause the same damage whether done for routine, diagnostic or "entertainment" purposes.
Elevated Maternal Temperatures Cause Birth Defects
Understanding what happens when the fetus's temperature increases, whether caused by an elevation in maternal core temperature or by the more local effect of ultrasound, is the key to appreciating prenatal ultrasound risks. An individual's body temperature varies throughout the day due to various factors such as circadian rhythms, hormone fluctuations and physical exertion. While people may have up to 1.5° F in each direction of what is considered a "normal" core temperature, the overall average among people is 98.6° F. An increase of only 1.4° F to 100° F can cause headaches, body aches and fatigue, enough to get the individual excused from work. A temperature of 107 F can cause brain damage or death.
A core temperature of about 98.6° F is important because that is the point at which many important enzyme reactions occur. Temperature affects the actual shape of the proteins that create enzymes, and improperly shaped proteins are unable to do their jobs correctly. As factors such as the amount of heat or duration of exposure increase, enzyme reactions become less efficient until they are permanently inactivated, unable to function correctly even if the temperature returns to normal.(18)
Because temperature is critical to proper enzyme reactions, the body has built-in methods to regulate its core temperature. For instance, when it is too low, shivering warms it up; when it is too high, sweating wicks off the heat. For obvious reasons, fetuses cannot cool off by sweating. However, they have another defense against temperature increases: Each cell contains something called heat shock (HS) proteins that temporarily stop the formation of enzymes when temperatures reach dangerously high levels.(19)
Complicating the issue is the fact that ultrasound heats bone at a different rate than muscle, soft tissue or amniotic fluid.(20) Further, as bones calcify, they absorb and retain more heat. During the third trimester, the baby's skull can heat up 50 times faster than its surrounding tissue (21), subjecting parts of the brain that are close to the skull to secondary heat that can continue after the ultrasound exam has concluded.
Elevated temperatures that might only temporarily affect the mother can have devastating effects on a developing embryo. A 1998 article in the medical journal Cell Stress & Chaperones reported that "the HS response is inducible in early embryonic life but it fails to protect embryos against damage at certain stages of development." The authors noted, "With activation of the HS response, normal protein synthesis is suspended…but survival is achieved at the expense of normal development."(22)
Autism, Genetics and Twin Studies
What does elevated body temperature have to do with autism? Geneticists are trying to crack the DNA mysteries behind ASD. Recently researchers linked two mutations of the same X chromosome gene to autism in two unrelated families, although they do not yet understand at what stage these genes were damaged.(23) Because sibling and twin studies show a higher prevalence of autism among children in families with one autistic child, geneticists expected to find inherited factors, but despite millions of dollars invested in the search, no clear explanation indicates that ASD is inherited. Perhaps scientists need look no further than at the thermal effects of ultrasound for many answers.
If prenatal ultrasound is responsible for some cases of autism, it stands to reason that if one twin were autistic, the other would have a high probability of being affected, since both would have been exposed to ultrasound at the same time. In both identical and fraternal twins, one twin could be more severely affected than the other if he or she happened to take the brunt of the heat or sound waves. In the case of fraternal twins, since autism strikes males between three to five times more often than females, the sex of the twins also could make a difference in outcome.
A 2002 study showed that simply being a twin substantially increased the likelihood of autism, making twinning a risk factor.(24) Could this increased twin risk factor have to do with the practice of giving mothers with multiple gestations more ultrasounds than those expecting single births? While not discounting the role genetics may play in autism, the possible impact of prenatal ultrasound deserves serious consideration.
Ultrasound Warnings Unheeded
The idea that a prenatal ultrasound can be hazardous is not new. The previously mentioned 1982 WHO report, in its summary "Effects of Ultrasound on Biological Systems," stated that "…animal studies suggest that neurological, behavioral, developmental, immunological, haematological changes and reduced fetal weight can result from exposure to ultrasound."(25)
Two years later, when the National Institutes of Health (NIH) held a conference assessing ultrasound risks, it reported that when birth defects occurred, the acoustic output was usually high enough to cause considerable heat.(26). Although the NIH has since stated that the report "is no longer viewed…as guidance for current medical practice," the facts remain unchanged.
Despite the findings of these two major scientific gatherings, in 1993 the FDA approved an eight-fold increase in the potential acoustical output of ultrasound equipment (27), greatly increasing the possibility of disastrous pregnancy outcomes caused by overheating. Can the fact that this increase in potential thermal effects happened during the same period of time the incidence of autism increased nearly 60-fold be merely coincidental?
Hot Tubs, Steam Rooms, Saunas and Maternal Fevers
If the culprit is heat, then what about other situations in which heat impacts pregnancy? A 2003 study titled, "A report of heat on embryos and fetuses" in the International Journal of Hyperthermia states, "hyperthermia during pregnancy can cause embryonic death, abortion, growth retardation and developmental defects."(28) It further states, "An elevation of maternal body temperature by 2 degrees Centigrade [3.6 degrees Fahrenheit] for at least 24 hours during fever can cause a range of developmental defects."(29) The report noted that necessary data to draw conclusions on exposure times less than 24 hours were lacking (30), leaving open the possibility that elevated maternal temperatures for shorter periods may adversely affect fetuses.
A study reported in the Journal of the American Medical Association (JAMA) found that "women who used hot tubs or saunas during early pregnancy face up to triple the risk of bearing babies with spina bifida or brain defects."(31). Hot tubs and baths present greater dangers than other heat therapies such as saunas and steam rooms because the immersion in water foils the body's attempt to cool off via perspiration, in much the same way fetuses cannot escape elevated temperatures in the womb.
All of this taken together establishes the fact that heat, whether caused by elevated maternal temperature or by an ultrasound transducer that remained over one area too long, can set into motion damaging changes in a developing baby. Using common sense, why would anyone think that intruding upon the continuous, seamless development of the fetus, which has for millions of years completed its work without assistance, be without consequences?
Vaccine and Thimerosal Controversy
Despite long-standing evidence that ultrasound induces thermal effects and that thermal effects can harm fetal brain development, the cause of autism has remained so elusive to researchers that many autism societies use a puzzle piece as part of their logos. Particularly confounding is the fact that ASD plagues the children of high-income, well-educated families who have the best obstetrical care money can buy. Why would women who took their prenatal vitamins, observed healthy diets, refrained from smoking or drinking and attended all regularly scheduled prenatal visits bear children with profound neurologically based problems?
Some believe that childhood vaccines, at first available only to those who could afford them, cause autism. Many vaccines contained thimerosal, a mercury-based preservative, which was thought to have a cumulative neurotoxic effect on children, especially as the number of childhood vaccines increased during the same period of years that the prevalence of autism increased. However, after an exhaustive review in 1999, the FDA found no evidence of harm in the use of thimerosal in childhood vaccines.(32)
Despite those findings, that same year the FDA, NIH, CDC, Health Resources and Services Administration (HRSA) and American Academy of Pediatrics (AAP) together urged vaccine manufacturers to reduce or eliminate thimerosal in childhood vaccines.(33) Pharmaceutical companies complied, and ultimately reduced the infant thimerosal exposure by 98%.(34)
Interestingly, not only did autism rates fail to decrease, they continued to increase. ASD increases are between 10 to 17 percent every year, according to the Autism Society of America (35), indicating that thimerosal is not to blame.
Thimerosal was not the only area of concern in the vaccine-autism controversy. Many people believed that a correlation existed between the triple vaccine MMR (mumps, measles and rubella) and ASD. However, a large, retrospective epidemiological study of more than 30,000 children in Japan between 1988 and 1996 found that the autism rate continued to climb after the vaccine was withdrawn.(36) Those results were no different than the outcome of a 1999 study published in The Lancet, that showed no corresponding jump in autism in the UK after the introduction of the MMR vaccine.(37)
A 2001 study published in JAMA examining California autism and MMR vaccination rates said the results did "not suggest an association between MMR immunization among young people and an increase in autism occurrence."(38) While concerns about vaccines and mercury exposure should not be dismissed, evidence to date does not implicate either one as a major factor in the explosion of ASD cases.
Global Autism Epidemic
Statistics on the increase of autism worldwide among industrialized nations show that it has emerged in just the last few decades across vastly different environments and cultures. What do countries and regions with climates, diets and exposure to known toxins as disparate as the US, Japan, Scandinavia, Australia, India and the UK have in common? No common factor in the water, air, local pesticides, diet or even building materials and clothing can explain the emergence and relentless increase in this serious, life-long neurodevelopmental disorder.
What all industrial countries do have in common is the quiet yet pervasive change in obstetrical care: All of them use routine prenatal ultrasound on pregnant women.
In countries with nationalized healthcare, where virtually all pregnant women are exposed to ultrasound, the autism rates are even higher than in the US, where due to disparities in income and health insurance, some 30 percent of pregnant women do not yet undergo ultrasound scanning.
The Changes in Ultrasound
In considering initial studies indicating that prenatal ultrasound is safe, one must factor in the ways in which the technology and its applications have continually changed and how that has altered the potential exposure of unborn children. Besides the huge increase in allowable acoustic output in the early 1990s, the following changes have made the field of prenatal ultrasound riskier than ever:
* The number of ultrasound scans conducted during each pregnancy has increased, with women often receiving two or more scans even in low-risk situations.(39) Women in "high-risk" situations may receive many more scans—which, ironically, may raise their risk.
* The range of time within an embryo or fetus's development when ultrasound is performed has extended to very early in the first trimester and continues into the third trimester, right up to delivery. Fetal heart monitors that are used prior to delivery—sometimes for hours—have not been shown to reduce neurological problems and may increase them.(40)
* The development of the vaginal probe, which positions the beam of sound much closer to the embryo or fetus, may put it at higher risk.
* The use of Doppler ultrasound, which is used to study blood flow or to monitor the baby's heartbeat, has increased. According to the 2006 Cochrane Database of Systematic Reviews, "routine Doppler ultrasound in pregnancy does not have health benefits for women or babies and may do some harm."(41)
Increasingly Common Birth Defects
Dr. Rakic's research team, cited earlier in this article for its recent study on mouse brains and ultrasound, pointed out that "the probe was held stationary for up to 35 minutes, meaning that essentially the entire fetal mouse brain would have been continually exposed to the ultrasound for 35 minutes…in sharp contrast to the duration and volume of the human fetal brain exposed by ultrasound which will typically not linger on a given tissue volume for greater than one minute."(42) This is an excellent point, which is worth pursuing.
One of the most popular non-medical uses of ultrasound, which can extend a medically indicated session, is to determine the sex of the baby.
# Could this have a connection to the increase in birth defects involving the genitals and urinary tract?
The March of Dimes says that these types of birth defects affect "as many as 1 in 10 babies," adding that "specific causes of most of these conditions is unknown."(43)
Following this line of thought, consider what other parts of the body are scrutinized by ultrasound technicians, such as the heart, where serious defects have soared nearly 250 percent between 1989 and 1996.(44) The list of unexplained birth defects is not a short one, and in light of what is emerging about prenatal ultrasound, scientists should take another look at all recent trends, as well as the baffling 30% increase in premature births since 1981, now affecting one in every eight children (45), with many showing subsequent neurological damage.(46)
Although many claim that ultrasound benefits outweigh the risks, that statement has no basis and much evidence is to the contrary. A large randomized trial of 15,151 pregnant women, conducted by the RADIUS Study Group, found that in low-risk cases, high-risk subgroups and even in cases of multiple gestations or major anomalies, the use of ultrasound did not result in improved outcome in the pregnancies.(47) The argument that ultrasound is either reassuring to the parents or provides an early opportunity for bonding pales in the face of the possible risks that are emerging as new data become available. Parents and health practitioners may not be able to easily turn away from this window on the womb and resume more traditional practices in obstetrics and midwifery. However, with the disturbing trend in autism and other equally troubling, unexplained birth-related trends, it does not make sense to blindly employ a technology that is not reliably safe for unborn babies.
Caroline Rodgers
Editor's Note: Read more about ultrasound on our Web site:
* Ultrasound: Weighing the Propaganda Against the Facts - by Beverley Lawrence Beech
* Ultrasound: More Harm than Good? - by Marsden Wagner
* Search more about ultrasound.
References:
1. "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.
2. "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.
3. "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.
4. "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.
5. 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.
6. "Ultrasound Can Affect Brain Development." Truth Out Issues. www.truthout.org/issues_06/080806HA.shtml. Accessed 25 Sep 2006.
7. Ibid.
8. 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.
9. 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.
10. 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.
11. 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.
12. Ibid.
13. 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.
14. Clancy, B., R.B. Darlington and B.L. Finlay. 2001. Translating developmental time across mammalian species. Neuroscience 105(1): 7–17.
15. Ibid.
16. See note 9 above.
17. See note 13 above.
18. Wilson, D.E. 2004. "Body Function Dependent On Body Temperature." In Wilson's Temperature Syndrome—A Reversible Low Temperature Problem. eBook. www.wilsonsthyroidsyndrome.com/eBook/Chapters/02Temp.cfm. Accessed 19 Sep 2006.
19. "How enzymes work." Biotopics. www.biotopics.co.uk/other/enzyme.html. Accessed 19 Sep 2006.
20. "The ultrasound procedure: Physical effects and research." Birth. www.birth.com.au/class.asp?class=6610&page=5. Accessed 23 Sept 2006.
21. Barnett, S.B. "Can diagnostic ultrasound heat tissue and cause biological effects?" In S.B. Barnett and G. Kossoff, eds. 1998. Safety of Diagnostic Ultrasound. Carnforth, UK: Parthenon Publishing.
22. Edwards, M.J. 1998. Apoptosis, the heat shock response, hyperthermia, birth defects, disease and cancer. Where are the common links? Cell Stress Chaperones 3(4): 213–20.
23. Klauck, S.M., et al. 2006. Mutations in the ribosomal protein gene RPL10 suggest a novel modulating disease mechanism for autism. Mol Psychiatry. advance online publication 29 August 2006. doi:10.1038/sj.mp.4001883.
24. Betancur, C., M. Leboyer and C. Gillberg. 2002. Increased Rate of Twins among Affected Sibling Pairs with Autism. Am J Hum Genet 70: 1381–83.
25. See note 4 above.
26. "Diagnostic Ultrasound Imaging in Pregnancy." National Institutes of Health Consensus Statement Online. 5(1): 1–16.
27. See note 16 above.
28. Edwards, M.J., R.D. Saunders and K. Shiota. 2003. Effects of heat on embryos and foetuses. Int J Hyperthermia. 19 (3): 295–324.
29. Ibid.
30. Ibid.
31. Milunsky, A., et al. 1992. Maternal heat exposure and neural tube defects. JAMA 268(7): 882–85.
32. "Thimerosal in Vaccines." U.S. Food and Drug Administration. www.fda.gov/cber/vaccine/thimerosal.htm. Accessed 21 Sep 2006.
33. Ibid.
34. "Thimerosal and Vaccines." Centers for Disease Control. www.cdc.gov/nip/vacsafe/concerns/thimerosal/faqs-thimerosal.htm#3. Accessed 27 Sep 2006.
35. "Facts and Statistics." Autism Society of America. www.autism-society.org/site/PageServer?pagename=FactsStats. Accessed 21 Sep 2006.
36. Honda, H., Y. Shimizu and M. Rutter. 2005. No effect of MMR withdrawal on the incidence of autism: a total population study. J Child Psychol Psychiatry 46(6): 572–79.
37. Taylor, B, et al. 1999. Autism and measles, mumps, and rubella vaccine: no epidemiological evidence for a causal association. Lancet 353(9169): 2026–29.
38. Dales, L., S.J. Hammer and N.J. Smith. 2001. Time Trends in Autism and in MMR Immunization Coverage in California. JAMA 285(22): 1183–85.
39. Stephens, M.B. 2000. American Family Physician Conference Highlights: Majority of Pregnant Women Want Prenatal Ultrasound. Am Fam Physician (62)12: 2665.
40. Wagner, M., and M.G. Wagner. 1994. Pursuing the Birth Machine, 1st ed. French's Forest, Australia: James Bennett Pty Ltd.
41. Bricker, L., and J.P. Neilson. 2006. "Routine Doppler ultrasound in pregnancy." The Cochrane Collaboration 3. www.cochrane.org/reviews/en/ab001450.html. Accessed 23 Sep 2006.
42. Smith, M. 2006. "Ultrasound Affects Development of Murine Brains." Medpage Today. www.medpagetoday.com/Radiology/GeneralRadiology/tb/3882. Accessed 13 Aug 2006.
43. "Genital and Urinary Tract Defects." March of Dimes. www.marchofdimes.com/printableArticles/4439_1215.asp. Accessed 27 Aug 2006.
44. "Healthy from the Start." 1999. The Pew Charitable Trusts (Environmental Health Commission). www.pewtrusts.com/pdf/hhs_healthy_from_start.pdf. Accessed 25 Sep 2006.
45. Behrman, R.E., and A.B. Stith, eds. 2006. Preterm Birth: Causes, Consequences, and Prevention. Washington, D.C.: National Academies Press. http://newton.nap.edu/catalog/11622.html. Accessed 20 Sep 2006.
46. "New research offers clues to prevent brain damage in premature babies." 2006. Medical News Today. www.medicalnewstoday.com/medicalnews.php?newsid=28786. Accessed 25 Sep 2006.
47. Ewigman, B.G., et al. 1993. Effect of Prenatal Ultrasound Screening on Perinatal Outcome. N Engl J Med 329(12):821–27.
Subscribe to:
Posts (Atom)
