I don’t know about you, but my impression of sonograms . . .
Going into my first pregnancy was that they were important for three reasons:
1. Making sure potential problems are detected to ensure the best possible outcome
2. Bonding + getting to show off baby’s first pic
3. Knowing what color to paint the nursery
Then one day, during a conversation with my chiropractor at a routine visit, five words changed everything. I was bubbling over with excitement about finding out, and she slipped in five words.
It’s fun to wait, too.
Really, what’s fun about WAITING?
So I asked, and she pointed me to research that made me think more deeply about my decision. Today I’m going to share that research, along with insights from other healthcare providers, including doctors and midwives.
Now, please keep in mind that – as I wrote in my posts on the Vitamin K shot, Glucola, being GBS positive, and other birth related subjects – “Best Boo-Boo Kisser South Of Puckett’s Gas Station” is about as official as things get for me professionally. I am not a doctor, this is not medical advice, and your decision is completely up to you. If you need some convincing on this, read my full disclaimer where I say it over and over again.
So what did I get wrong?
During the conversation with my chiropractor – who went on to become a doula, midwife and dear friend who helped me birth my winter solstice baby and the boom boom thomp boy – I discovered pretty quickly that I’d made some inaccurate assumptions. First, statistically speaking routine sonograms do not improve birth outcomes. (source) Second, I assumed that the technology carried virtually no risk – wrong again.
Oh and that third one about the color of my baby’s nursery? She ended up cosleeping with us using these safety guidelines, and the only person that slept in the nursery was our cat.
What is ultrasound, exactly?
Originally used by the military to detect submarines via SONAR, ultrasound technology bounces ultra high frequency sound waves off the tissues, bones, etc. of a baby in the womb, then uses the pattern created by the different surfaces to generate an image.
According to Lauren Feder, MD, “Modern ultrasound energy intensities are higher than ultrasound of earlier decades. In obstetrics the following ultrasounds and energy exposures are used:
- Standard scan. The standard scan is used on the abdomen after early pregnancy. Provides a brief pulse ultrasound of lower exposure
- Trans Vaginal ultrasound. Used in early pregnancy. High exposure levels due to close proximity of probe to early developing fetus . . .
- Doppler ultrasound. Used by many obstetricians and midwives in stethoscopes, they provide relatively low exposure level.
- Fetal monitors: used in late pregnancy and during labor to monitor baby and heart level.
- 3-D Ultrasound. To generate 3-D images of the developing fetus. High level of exposure.
- 4-D or Dynamic 3-D Ultrasound: Uses specially designed scanners to look at the face and movements of the baby. High level of exposure.
- Fetal Echocardiography: Uses ultrasound waves to assess the baby’s heart in suspected congenital heart defects.” (emphasis mine)
Wait, isn’t it just like a high-tech camera?
No. Unlike a camera which can take pictures without producing any changes in the subject photographed, sonograms can “promote cell growth, cell destruction, alter membrane fluidity (e.g., poke temporary holes in cell membranes), and alter a cell’s activity such as causing a neuron to fire” explains Dr. Manuel Casanova, a neuroscientist at the University of Louisville, adding that “It turns out it’s not just a picture after all.” (source)
What are the risks of ultrasound?
That’s a question doctors and researchers seem to be struggling with. The last devices used in a large, controlled human epidemiological studies were developed before 1991 – their acoustic output upper limit was 94 mW/cm2. Ultrasound devices now in use can have an acoustic output of up to 720 mW/cm2, which is more than seven times higher.
In her book, Gentle Birth, Gentle Mothering, Sarah Buckley, M.D. discusses problems with several “gold-standard” randomized, controlled human studies which reported no difference in outcomes between scanned and unscanned children other than a higher incidence of left-handedness in boys. (Left-handedness is normal for some children, but is under certain circumstances “marker of damage or disruption to the developing brain,” she explains. )
In her words, it is “difficult to gain reassurance from these trials because, for example, in the Swedish study, 35 percent of the supposedly unexposed group actually had a scan (69),” and in the trial which found that scanning did not have a negative impact the exposure time was only three minutes. In other words, the control group in the the Swedish study was not a true control group, and the second study is not representative of clinical practice. (The typical scan is about 30 minutes.)
Dr. Buckley does mention several other studies worth noting, though:
- “A large UK study found that healthy mothers and babies randomized to two or more Doppler scans to check the placenta, beginning in midpregnancy, had more than double the risk of perinatal death compared to babies unexposed to Doppler. (66)” (source, emphasis mine)
- Another Australian study suggest that Doppler ultrasound may actually increase the likelihood of developing a condition it’s used to detect. Babies who were randomly selected to receive “five or more Doppler ultrasounds during pregnancy were more likely than babies . . . [randomly selected to receive] . . . routine (pulsed) ultrasound to develop intrauterine growth retardation (IUGR) – a condition that ultrasound is often used to detect. (64) This may be related to higher exposure levels with Doppler, as more IUGR has been found in high-exposure animal studies, but not in lower-exposure human studies using pulsed ultrasound.” (source)
- Also discussed are several “Single or small studies that have shown that possible adverse effects include . . . preterm labor or miscarriage (26) (62), low birth weight (63) (64), poorer condition at birth (65), perinatal death (66), dyslexia (67), delayed speech development (68), and non-right handedness (69) (70) (71) (72)” – which as mentioned before is completely normal in many individuals, but may also indicate a disruption in brain development for some who were originally predisposed to right-handedness.
Yale Researchers: Ultrasound impairs brain development in mice
In this study headed by Dr. Pasko Rakic of Yale University, researchers found that mice who were exposed to 30 minutes of continuous ultrasound in utero showed impaired brain development. Dr. Rakic noted that “the ultrasound parameters and total exposure time are comparable with or below those used by commercial medically nonindicated prenatal ultrasound videos.” Now, it’s tempting to think . . .
But those are mice! Mice aren’t people!
However, there’s a good reason to pay attention to this study. According to this article in Midwifery Today, neurodevelopmental defects in rats and other mammals should be of concern to expecting mothers “Because, as Cornell University researchers proved in 2001, brain development proceeds in the same manner ‘across many mammalian species, including human infants.’ 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. (3)”
Other Animal Studies To Consider
There are so many studies available, many which suggest caution, and some which indicate relative safety. Here are a few that Dr. Buckley mentions in Gentle Birth, Gentle Mothering:
- One study “found brain hemorrhages in mouse pups exposed in the womb to pulsed ultrasound at doses similar to those used on human babies.”
- “Other researchers found that a single ten-minute pulsed ultrasound exposure in pregnancy affected the locomotor and learning abilities of mouse offspring in adulthood, with a greater effect from longer exposure time.”
- A study “involving newborn rats, who are at a similar stage of brain development to humans at four or five months in utero, suggested that pulsed ultrasound may damage the myelin that covers nerves (50), indicating that the nervous system may be particularly susceptible to damage from this technology.”
- “Other experts in this area have expressed concern in relation to heating of the developing central nervous system, whose tissues are sensitive to damage by physical agents including heat. Barnett, a biomedical physicist, notes that heating of the fetal brain is more likely after the first trimester (three months), as the skull bone is more developed and can reflect and concentrate the ultrasound waves. (44)”
Do routine ultrasounds improve birth outcomes?
According to this meta-analysis, “Routine ultrasound scanning does not improve the outcome of pregnancy in terms of an increased number of live births or of reduced perinatal morbidity.” Several other studies support these findings.
Here’s an analysis of additional published research which concludes that “No routine ultrasound screening protocol improves outcomes (Haws et al. 2009). It can be surmised from other research that this is due to the incredible inaccuracy of ultrasound. A recent study found a full third or 34% of ultrasound fetal weight estimates to be outside of the expected +10% to -10% range (Hargreaves 2011). Another study from 2011 found that 1 in 23 (4%) of first trimester ultrasounds in which the woman was told there was no viable pregnancy were wrong and the fetus was fine and the pregnancy went to term (Abdallah et al. 2011). Ultrasound technology cannot reliably predict the presence of a nuchal cord, tell whether a nuchal cord is tight or determine anything regarding the likelihood of hypoxia, IUGR or stillbirth (Cohain 2010). Use of 3D Doppler color ultrasound specifically done to look for a cord in labor detected only 35% of cords around the neck, 60% of cords that were twice around the neck and had a 20% false positive rate, meaning the results said there was a cord around the neck in 20% of fetuses when there wasn’t (Bolten et al. 2009).”
The desire to ensure that “baby is okay” was certainly a powerful draw to sonograms for me. However, according to research collected by Sarah J Buckley, M.D.:
“[W]hile many women are reassured by a normal scan, RPU [routine prenatal sonograms] actually detects only between 17 and 85 percent of the 1 in 50 babies that have major abnormalities at birth. A recent study from Brisbane showed that ultrasound at a major women’s hospital missed around 40 percent of abnormalities, with most of these being difficult or impossible to detect. Major causes of intellectual disability such as cerebral palsy and Down’s syndrome are unlikely to be picked up on a routine scan, as are heart and kidney abnormalities.” (source)
There is also the risk of a “false positive,” which causes needless worry for some families.
Any special considerations for birth center or home births?
Care providers often strongly recommend that individuals who plan to birth out of the hospital have one scan to check for organ abnormalities. Though ultrasound does deliver both false positives and false negatives, if abnormalities are suspected and/or confirmed via additional testing, a hospital birth will likely be recommended so that care can be given immediately after delivery. (This section has been added due to input from a pediatrician and sonographer – thank you!)
Is it possible to minimize the risks of sonograms?
Ultrasound equipment keeps track of two readings to minimize as much risk as possible: the thermal index (TI) and mechanical index (MI). It is up to the sonographer to make sure the TI and MI stay within recommended ranges during ultrasound, but unfortunately many do not even know how to locate this information.
According to this article published at Contemporary OBGYN, “Unfortunately, the level of knowledge regarding ultrasound safety issues appears to be less than desirable. In a 2005 survey of attendees of European postgraduate obstetric ultrasound courses, only 22% and 11% of the participants could explain the TI and MI, respectively, and only 28% could locate this information on the ultrasound screen.33 A similar survey of American ultrasound operators conducted in 2007 revealed comparable results: 17.7% and 3.8% of the participants could describe the TI or MI, respectively, and 20.8% could locate this information on the display.” (emphasis mine)
If an ultrasound is planned, it might be wise to discuss in advance whether or not the sonographer has appropriate safety knowledge and enough experience to perform a thorough scan quickly. In Gentle Birth, Gentle Mothering, Dr. Buckley also suggests that parents have both the referring doctor and sonographer fill out this form to keep for the baby’s records. You can find a printable version of it here.
So did you get an ultrasound, Mommypotamus?
After everything I just shared you may be surprised to read that, so I’ll explain. When I was pregnant with my oldest, I underwent Doppler ultrasound (via a Sonicaid) to hear my baby’s heartbeat for the first time. Though magical in some ways, I remember noticing my belly physically grow warm during the procedure and asking if that was okay and normal. A few weeks later when I spoke with my chiropractor, I learned about the possible thermal effects of ultrasound and decided to forego future ultrasounds unless medically indicated.
For me, that meant waiting many more weeks to hear my baby’s heartbeat again using an old-fashioned fetoscope (a stethoscope for your belly.)
My labor with her was long, and though my midwives were excited about using their water-friendly fetoscope while I worked through contractions in the birth pool, they found that that they weren’t able to reliably pick up baby’s heartbeat. It could have been a defect in the scope or just inexperience, but regardless there came a point when they said that I either needed to get out of the tub and let them check on the baby or let them use the Doppler. Moving wasn’t really an option at the moment, so I let them use the Doppler. Wanting to honor my wishes as much as possible, they checked very quickly as needed (which was twice I think) while they encouraged and supported me.
With #2, the boom boom thomp baby, I opted out of all ultrasounds until birth, where I again allowed very brief use of the Doppler as needed.
And the bullseye baby? Well, I birthed him before anyone realized I’d made my way through transition, so no Doppler was needed.
The decision to have a sonogram (or not)
. . . . is a very personal one. A lot of health care providers feel that one sonogram at 20 weeks to rule out detectable problems carries a minimal amount of risk. Some feel they are more important when home birth is planned since the detection of certain abnormalities would make it unsafe to birth at home. Others express concern that neuronal migration changes observed in the Yale study may be similar to neuron growth patterns observed in individuals with autism. And finally, some have questions about research coming out of China which suggests that it may be wise to aim for lower exposure times when ultrasound is called for.
I am beyond thankful for the midwives who helped me determine when the benefits outweighed the risks for my situation, and of course the chiropractor who encouraged me to think more deeply about the decision in the first place. I shared this information not to convince you to do one thing or another, but pass along the information I found useful in my decision making process.
Though it is not for everyone, I discovered that in my case my chiropractor-turned-midwife was right – it was fun to be surprised!
Did you/will you have a routine ultrasound? Why or why not?
Photo Credit: Travis Isaacs