Pregnancy Sonograms and Ultrasounds: Risks vs. Rewards

There is something so exciting about seeing your little jelly bean bouncing around on the ultrasound screen, but is it safe for mother and baby?  The truth is that scientists have uncovered evidence suggesting that ultrasound scans on pregnant women can cause brain damage in their unborn babies.

A 2006 study shows that the frequent use of ultrasound causes brain abnormalities in the developing fetuses of mice. A small but significant number of neurons in the embryonic mouse brain do not migrate to the correct positions in the cerebral cortex if ultrasound is used often or for prolonged periods.

In 2001, 67% of pregnant women had at least 1 ultrasound, and in 2009, that percentage jumped to 99.8% with an average of 3 per woman.

“Clinical use of diagnostic ultrasound imaging during pregnancy has a long history of safety and diagnostic utility, as supported by numerous human case reports and epidemiological studies.  

However, there exist in vivo studies linking large but clinically relevant doses of ultrasound applied to mouse fetuses in utero to altered learning, memory, and neuroanatomy of those mice.”

Randomized studies point to potential increased incidence of low birth weight, delayed speech, poor school performance, dyslexia, and non-righthandedness.

Multiple Cochrane reviews have demonstrated a lack of perinatal mortality benefit for routine ultrasound in a normal pregnancy, and an increased risk of cesarean section with third trimester screening. A review of outcomes literature condemns ultrasound when used for dating, second trimester organ scan, biophysical profile, amniotic fluid assessment, and Doppler velocity in high and low risk pregnancies.

Scanning works by sending sound waves into your tissues. As these sound waves bounce off of your tissues, a picture can be created.

The sound waves are capable of producing the following physiological effects:

  • Increase in blood flow and temperature in local tissues
  • Production of gas bubbles that can put pressure on local tissues
  • Mechanical effects like movement of the fluid that surrounds your cells, which can also put pressure on local tissues

This sounds scary, and it is. There is risk and reward to everything, and being educated will help you to make the best decision for you.  Talk to your midwife about her recommendations, discuss research and options together to come up with a plan.

The reason that I share this information with you is this:

Avoid all unnecessary ultrasounds and sonograms.

In all actuality, healthy, low-risk pregnant women are recommended to only receive a sonogram at 20 weeks.  This scan should be done in a timely manner.  However, there are times when other scans are recommended to check on the baby.  

Let’s talk about the difference between a sonogram and an ultrasound.

A sonogram is the image generated during ultrasonography, which is a diagnostic imaging technique that uses ultrasound to visualize anything inside the body. Ultrasound is sound with a frequency above the range audible to humans, about 20 kHz.  Both terms are used interchangeably by most people, but in layman’s terms an ultrasound is using sound waves to see or hear something inside the body. A sonogram is the actual visual picture of what the ultrasound is picking up.  

The following are ultrasound types commonly used in pregnancy:

Standard Ultrasound – Traditional ultrasound exam which uses a transducer over the abdomen to generate 2-D images of the developing fetus.

Advanced Ultrasound – This exam is similar to the standard ultrasound, but the exam targets a suspected problem and uses more sophisticated equipment.

Doppler Ultrasound –  This imaging procedure measures slight changes in the frequency of the ultrasound waves as they bounce off moving objects, such as blood cells.

3-D Ultrasound –  Uses specially designed probes and software to generate 3-D images of the developing fetus.

4-D or Dynamic 3-D Ultrasound – Uses specially designed scanners to look at the face and movements of the baby prior to delivery.

Fetal Echocardiography – Uses ultrasound waves to assess the baby’s heart anatomy and function. This is used to help assess suspected congenital heart defects.

Your doctor or midwife will likely use the Doppler during each prenatal visit to pick up the baby’s heartbeat.  Generally, they keep it short and use this as reassurance to you that baby is doing well.  This is very common, but can be denied if you feel the urge not to have it done.  

She may recommend one or more sonogram throughout your pregnancy, for a variety of reasons.  You may not know when you conceived or may have suffered previous miscarriages.  You may be over the age of 35 and your doctor requires extra screening.  There may be genetic reasons for extra scans, or a low lying placenta that could threaten a vaginal delivery.  Your little fetus may stubbornly decide to lay transverse and a late sonogram is needed to see position.  There are numerous reasons to receive a recommendation for additional sonograms other than the 20-week anatomy scan.  

Remember that the choice is yours, but by keeping an open and trusting dialogue with your midwife, she can be a wonderful source of information to aid you in your decisions.

Research shows the screening ultrasonography results in no clinically significant benefit, and the American College of Obstetrics and Gynecology do not recommend routine prenatal ultrasound.