Pregnancy: are ultrasound scans dangerous for the baby?

With Sophie-Hélène Zaimi, Radiologist

When should I have an ultrasound scan?

In the case of a basic pregnancy with no particular complications, only 3 ultrasounds are required and are covered by social security. The first ultrasound is called the "dating ultrasound", and takes place between the 11th and 13th week of amenorrhea, i.e. around 3 months into the pregnancy. It lasts 30 minutes and is used to s'ensure that the fetus is viable, by examining the head, thorax, limbs, abdomen, various organs and heart of the fetus. The ultrasound also checks for abnormalities and malformations. During this first ultrasound, the pregnant woman will be checked for malformations or fibroids in the ovaries, which could have an impact on the pregnancy.

The second ultrasound is called the morphological ultrasound. It is performed between the 22nd and 24th week of amenorrhea. This corresponds to around the 5th month. During this ultrasound, several measurements are taken: the diameter and circumference of the head, measurement of the brain, measurement of the lateral ventricles, measurement of the nasal bones. It will also examine all the organs in detail, the speed of the blood in the cord and in the uterine arteries. It is during this ultrasound that the baby's sex can be determined.

Finally, the third and last ultrasound s is usually performed at around 7 to 8 months, between 31 and 33 weeks of amenorrhea. During this ultrasound, the doctor measures the baby and checks its growth. He also checks all the organs, as well as the limbs, and takes some measurements. Thanks to these measurements, the doctor is able to estimate the baby's full-term weight. 

Why are ultrasounds useful?

The ultrasound scanner uses ultrasonic waves. Ultrasound waves are not harmful to health, and have no impact on the tissues and organs of the human body. Pregnant women undergo ultrasound scans to diagnose and monitor pregnancy, as well as to check for malformations, and so on.

There are 3 types of ultrasound:

- The most widely used ultrasound is 2D, i.e. a single plane. This is the basic ultrasound technique used in all radiology centers.

- Secondly, some centers use 3D ultrasound, i.e. ultrasound in volume, to produce 3D images.

- And finally, there's 4D ultrasound, which adds the notion of temporality to volume. This is a dynamic ultrasound in which we see the baby in 3D over time, since the videos are of the order of 7 images per second.

3D ultrasound and 4D ultrasound are not really useful for diagnosis, but rather for parents. It allows them to see their baby. It has no impact on pregnancy follow-up or malformation diagnosis.

Are 3D and 4D ultrasound scanners dangerous for your baby's health?

Like 2D ultrasound, 3D and 4D ultrasound also use ultrasonic waves. As explained above, ultrasound waves are not harmful and therefore have no deleterious effects on human body cells, soft tissues or organs. Whether you have a 2D, 3D or 4D ultrasound scan, there will be no negative impact on you or your child.

Do repeated ultrasounds encourage regurgitation in newborns?

There's a common misconception that repeated ultrasound scans can cause regurgitation in newborns, but there's no scientifically proven link between repeated ultrasound scans and regurgitation in newborns.

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