Baby + Child, Pregnancy + Birth

A Deeper Look at Prenatal Ultrasounds

It’s easy to take prenatal ultrasounds for granted. They are such a deeply ingrained part of birth culture in Western medicine, that most women don’t even think twice about going in for several scans during the course of a pregnancy.

While routine ultrasounds are now considered a part of standard prenatal care in most developed countries, this technology is not as helpful, or benign as we have been led to believe. In her article, “Ultrasound Scans — Cause for Concern,” Dr. Sarah Buckley states, “Although ultrasound may sometimes be useful when specific problems are suspected, my conclusion is that it is at best ineffective and at worse dangerous when used as a ‘screening tool’ for every pregnant woman and her baby,” (2005).

Ultrasound machines emit high frequency sound waves, which create a picture of the tissues being scanned from the “echo” of these waves. Dr. Buckley explains, “ordinary scans use pulses of ultrasound that last only a fraction of a second, with the interval between waves being used by the machine to interpret the echo that returns. In contrast, Doppler techniques, which are used in specialised scans, fetal monitors and hand-held fetal stethoscopes feature continuous waves, giving much higher levels of exposure than ‘pulsed’ ultrasound” (2005).

One application of prenatal ultrasound is what is commonly referred to as “transvaginal” ultrasound. In this type of scan, the transducer is inserted into the vagina. This is typically done in very early pregnancy, when an abdominal ultrasound would result in a low-quality picture of the baby. The problem with this type of scan is that there is very little tissue to protect the baby from the exposure, and it is done at a time when the developing baby is particularly vulnerable (Buckley, 2005).

While many women do have first trimester ultrasounds, the American College of Obstetricians and Gynecologists (ACOG) does not consider this standard, stating that it is too early to see how the fetus is developing. Their recommendation is to have “at least one” ultrasound during the entire course of a pregnancy, typically between 18-22 weeks (ACOG).

It is interesting to note that there is actually little evidence that the use of ultrasounds during pregnancy improves outcomes. The authors of a meta-analysis found “Routine ultrasound scanning does not improve the outcome of pregnancy in terms of an increased number of live births or of reduced perinatal morbidity” (Bucher and Schmidt, 1993).

Similarly, a review of evidence on routine prenatal ultrasounds concluded “Existing evidence does not provide conclusive evidence that the use of routine umbilical artery Doppler ultrasound, or combination of umbilical and uterine artery Doppler ultrasound in low-risk or unselected populations benefits either mother or baby” (Alfirevic, Zarko et al., 2010).

Despite the lack of conclusive scientific data proving the benefits of ultrasounds, there are several reasons that they are recommended during pregnancy.

Predicting baby’s due date

Studies have found that determining baby’s due date using the last menstrual period is just as accurate as ultrasound dating, indicating an ultrasound is not truly necessary for this purpose.

Determining baby’s sex

One reason many women look forward to is ultrasounds is to find out their baby’s gender. However, ultrasounds are not the only way to determine this. Blood testing is another option for parents who want to know the sex of their baby in utero. Waiting until the baby is born to find out is obviously also an option, but in the age of instant gratification, this is fairly uncommon.

Ruling out or confirming ectopic pregnancy

Ectopic pregnancy is a life-threatening condition where a fertilized egg implants outside of the uterus, most commonly in the fallopian tube. However, it will present with other signs in the first 8-10 weeks of pregnancy, including vaginal bleeding, dizziness or weakness, and pain in the pelvis, lower abdomen & lower back. If these symptoms occur, doctors can then use ultrasound to confirm the suspected issue.

Detecting placenta previa

Placenta previa is a condition where the placenta attaches low in the uterus and may partially or fully cover the cervix. As with most pregnancy complications it will usually present with symptoms, and typically causes bleeding after 20 weeks of pregnancy. It is interesting to note that one study found that detecting placenta previa early in pregnancy with ultrasound didn’t change fetal outcomes. This study actually found that that of the 250 women who were diagnosed with placenta previa, 246 of them ended up not having it at delivery. Studies have shown that for 80-100% of women diagnosed with placenta previa through routine ultrasounds, the placenta will move up and not cause issues during birth (Kresser, 2011).

Connecting & bonding with baby

It is quite common for a woman to desire an ultrasound because they feel like it helps them bond with their baby. In more recent years, this desire has escalated into gathering mementos via ultrasound photos and videos. However, the FDA warns against conducting ultrasound merely for this purpose, stating “because of the particular concern for effects on the fetus, organizations such as the American Institute of Ultrasound in Medicine have advocated prudent use of ultrasound imaging in pregnancy. Furthermore, the use of ultrasound solely for non-medical purposes such as obtaining fetal ‘keepsake’ videos has been discouraged.”

While taking a peek at baby via ultrasound can be a way for a woman to connect with the life forming in her womb, there are many other ways to bond with baby before birth. Here are a few ideas:

  • Keep a pregnancy journal
  • Talk and sing to baby
  • Gently rub or massage your belly
  • Play music for baby
  • Have a warm bath or go for a walk to give yourself a chance to reflect on the experience of pregnancy
  • Take time to relax and tune into your needs

Ensuring that baby is developing normally

It is worth mentioning that ultrasounds only actually detect 17- 85% the major abnormalities that 1 in 50 babies have at birth. A study found that at one major women’s hospital, ultrasound scans missed around 40% of abnormalities — most of which were difficult or impossible to detect (Buckley, 2005).

There is also a small possibility of having a abnormality incorrectly diagnosed. One study found that 1 in 200 babies aborted due to major abnormalities had a less severe post-mortem diagnosis than was predicted by the ultrasound, indicating that the termination was likely not necessary. This study also showed that 2.4% of babies diagnosed with major malformations before birth (using ultrasound) who were not aborted had conditions that were either severely under or over diagnosed (Buckley, 2005).

While ultrasound certainly may be a helpful tool for diagnosing potential issues with a baby’s development, for some mothers it causes unnecessary worry and stress, which can certainly negatively impact their experience of pregnancy as well as their overall mental well-being. In addition to the possibility of incorrectly diagnosed abnormalities, there is also the chance that the results of the scan will create more uncertainty. One study of women with high risk pregnancies found that almost 10% of scans had results that were “uncertain.” This same study found that women who has received questionable a diagnosis during their pregnancy continued to experience anxiety 3 months postpartum (Buckley, 2005).

Is ultrasound safe?

Because ultrasounds are so highly utilized in prenatal care, it is often assumed that this is a completely safe technology. However, there is actually no definitive proof that this is the case.

According to the FDA, “Although ultrasound imaging is generally considered safe when used prudently by appropriately trained health care providers, ultrasound energy has the potential to produce biological effects on the body. Ultrasound waves can heat the tissues slightly. In some cases, it can also produce small pockets of gas in body fluids or tissues (cavitation). The long-term consequences of these effects are still unknown.”

American College of Obstetricians & Gynecologists (ACOG) states, “No links have been found between ultrasound and birth defects, childhood cancer, or developmental problems later in life. However, it is possible that effects could be identified in the future. For this reason, it is recommended that ultrasound exams be performed only for medical reasons by qualified health care professionals. Casual use of ultrasound during pregnancy should be avoided” (ACOG).

There is ample scientific data suggesting that the effects of ultrasound on living tissues may be cause for concern. Buckley states, “Studies on humans exposed to ultrasound have shown that possible adverse effects include premature ovulation, preterm labour or miscarriage, low birth weight, poorer condition at birth, perinatal death, dyslexia, delayed speech development, and less right-handedness. Non right-handedness is, in other circumstances, seen as a marker of damage to the developing brain. One Australian study showed that babies exposed to 5 or more doppler ultrasounds were 30% more likely to develop intrauterine growth retardation (IUGR) — a condition that ultrasound is often used to detect” (2005).

One study on newborn rats who were at a similar stage of brain development as humans are at when they are 4-5 months in utero, found that ultrasound can damage the myelin sheath around nerves (Ellisman et al., 1987). It has also been shown that exposing mice to ultrasound in dosages typical of prenatal scans caused a 22% reduction in the rate of cell division and doubled the rate of apoptosis, or cell death (Stanton et al., 2001).

Another study examining cells grown in the lab showed that abnormalities caused by ultrasound exposure persisted for several generations (Liebeskind et al., 1979).

Robin Mole, author of “Possible Hazards of Imaging and Doppler Ultrasound in Obstetrics” states, “if exposure to ultrasound… causes death of cells, then the practice of ultrasonic imaging at 16 to 18 weeks will cause loss of neurones [brain cells] with little prospect of replacement of lost cells…The vulnerability is not for malformation but for maldevelopment leading to mental impairment caused by overall reduction in the number of functionning neurones in the future cerebral hemispheres” (Mole, 1986).

In 50 Human Studies, in Utero, Conducted in Modern China, Indicate Extreme Risk for Prenatal Ultrasound: A New Bibliography, Jim West describes the findings of Professor Ruo Feng of The Institute of Acoustics, Nanjing University, and editor of The Chinese Journal of Ultrasound in Medicine and Biology, and member of the World Federation of Ultrasound in Medicine and Biology, stating “Ruo Feng, who reviewed many of the studies, stipulated that routine ultrasound be avoided. Only if there were exceptional medical indications should ultrasound be allowed, and at minimum intensity. Sessions should be very brief, no more than 3 minutes, 5 minutes at most. Multiple sessions should be avoided because hazards are cumulative. Human studies had found sensitive organs damaged at 1 minute exposure” (2015).

As stated in a 2009 article on ultrasound published in Ultrasound in Obstetrics & Gynecology, “There is no such thing as zero risk, and absence of evidence of harm is not equivalent to evidence of absence of harm” (Bergen).

One issue with studying the effects of ultrasound is that there is a huge range of possible outputs from any given machine. “Modern machines can give comparable ultrasound pictures using a lower, or a 5,000 times higher dose, and there are no standards to ensure that the lowest dose is used. Because of the complexity of machines, it is difficult to even quantify the dose given in each examination,” states Buckley (2005).

According to the FDA “while ultrasound is generally considered to be safe with very low risks, the risks may increase with unnecessary prolonged exposure to ultrasound energy, or when untrained users operate the device” (FDA).

I realize all of this information might be overwhelming for someone who has unknowingly and unnecessarily exposed their baby to excessive ultrasounds. Unfortunately, because it is such a standard part of prenatal care, many women have several ultrasounds during the course of a pregnancy, with out ever considering the possibility of any risk. During my first pregnancy, I had 4 ultrasounds — including a very early transvaginal ultrasound around 6 weeks, one at 10 weeks when I started bleeding, a routine scan during my 2nd trimester, and a final scan that my midwife required around 35 weeks to “make sure” it was safe for me to have a home birth. I never even thought to question whether this was safe for my developing baby. Obviously, knowing what I know now, I would do things differently. And that’s why it felt so important to write this post. Women can’t make informed choices if they don’t know any better.

Ultimately, pregnant women should carefully weigh the risks of ultrasound versus the potential benefits. And if you do decide to get an ultrasound, there are a few important precautions you can take to help reduce the risk for baby, including:

  • Use ultrasound only when there is a suspected problem, instead of as a routine screening or check up.
  • Choose a skilled and knowledgeable ultrasound technician and minimize total exposure time.
  • Minimize the intensity of exposure — i.e. avoid Doppler, especially during the first trimester (Kresser, 2019).
  • If an abnormality is discovered, ask for a second opinion and as Dr. Buckley says, “remember that it’s your baby, your body and your choice” (2005).

In conclusion, I’ll leave you with this advice from the author of “Ultrasonic imaging: safety considerations,” Gail ter Haar. “Above all, [obstetric] ultrasound scans should only be carried out when there is a clinical need, and only by fully trained professionals who understand the modality and its safe use” (2011).


ACOG. “Ultrasound Exams.” October 2021.

Alfirevic, Zarko et al. “Fetal and umbilical Doppler ultrasound in normal pregnancy.” The Cochrane database of systematic reviews, 8 CD001450. 4 Aug. 2010, doi:10.1002/14651858.CD001450.pub3

American Pregnancy Association. “Twins Pregnancy Symptoms.” 2021.

Bergen, Helse. “Ultrasound is not unsound, but a safety issue.” Ultrasound in Obstetrics & Gynecology (UOG), 33: 502-505. 2009.

Brogan, Kelly. “Human Studies Condemn Ultrasound.”

Brogan, Kelly. “Perils of Peeking into the Womb: Ultrasound Risks.”

Buckley, Sarah J. “Ultrasound Scans — Cause for Concern.” 2005.

Buckley, Sarah J. “Ultrasound Scans in Pregnancy – Your Questions Answered!” July 15, 2016.

Bucher, H.C., and Schmidt, J.G. “Does routine ultrasound scanning improve outcome in pregnancy? Meta-analysis of various outcome measures.” British Medical Journal 1993, 307:13.

Clark, Yolande. “Ultrasound Part 1.” Bauhauswife Podcast. Episode 12. April 10, 2018.

Clark, Yolande. “Unpacking Ultrasound Part 2.” Bauhauswife Podcast. Episode 13. April 28, 2018.

Ellisman MH, et al. “Diagnostic levels of ultrasound may disrupt myelination.” Experimental Neurology 1987; 98(1):78-92.

FDA. “Ultrasound Imaging.” September 28, 2020.

Howland, Genevieve. “The Truth About Baby Ultrasound.” Mama Natural. August 7, 2020.

Kresser, Chris. “Natural Childbirth IIa: Is Ultrasound Necessary & Effective in Pregnancy?” July 11, 2011.

Kresser, Chris. “Natural Childbirth IIb: Ultrasound Not as Safe as Commonly Thought.” June 7, 2019.

Lawrence Beech, Beverley. “Ultrasound: Weighing the Propaganda Against the Facts.” Midwifery Today, Issue 51.

Liebeskind D, et al. “Diagnostic ultrasound: effects on the DNA and growth patterns of animal cells.” Radiology 1979;131(1):177-84.

Marinac-Dabic D, et al. The safety of prenatal ultrasound exposure in human studies. Epidemiology 2002;13(3 Suppl):S19-22.

Mole R. Possible hazards of imaging and Doppler ultrasound in obstetrics. Birth 1986; 13 Suppl:23-33 suppl, p 26.

Saldaya, Emilee. “Unpacking Ultrasound With Yolande Clark.” Free Birth Society Podcast. May 29, 2018.

Stanton MT, et al. “Diagnostic ultrasound induces change within numbers of cryptal mitotic and apoptotic cells in small intestine.” Life Sciences 2001;68(13):1471-5.

ter Haar, Gail. “Ultrasonic imaging: safety considerations.” Interface Focus. 1(4): 686–697. August 6, 2011.

“Understanding Ultrasound.” Indie Birth. July 23, 2013.

West, Jim. 50 Human Studies, in Utero, Conducted in Modern China, Indicate Extreme Risk for Prenatal Ultrasound: A New Bibliography. April 30, 2015.

“What No One Ever Told You About Second Trimester Ultrasound.” Indie Birth Podcast. August 22, 2013.

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