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What is ultrasound and is it dangerous to the fetus?
Last reviewed: 06.07.2025
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Ultrasound - ultrasound examination.
Unlike X-ray examination, where ionizing radiation is used for diagnostics, ultrasound examination uses sound waves. Their frequency is below the threshold of perception, so they are not heard, but due to this they can be reflected from internal organs and return back to the sensor from where they were sent. In the sensor they are transformed and displayed on the monitor screen as an image. The principle of ultrasound diagnostics is similar to the hunt of bats, which, not seeing a butterfly in the dark, "see" its shadow with the help of ultrasound waves.
The tissues of the woman's body and the fetus have different densities and are located at different distances from the sensor, so the reflected sound waves look different, forming a picture that is quite understandable for an experienced ultrasound specialist.
Typically, ultrasound is performed three times during pregnancy.
Moreover, it is not recommended to conduct it before the 10th week of pregnancy, since it is during this period that the main organs of the future child are laid. And like any other physical phenomenon, ultrasound has certain properties and can somehow affect the fetus. Despite the fact that mass studies have been conducted that have shown that ultrasound is safe for the fetus, the World Health Organization (WHO) recommends conducting ultrasound no more than four times during pregnancy. The study of the effect of ultrasound on the fetus continues, and there is data that confirm the need for a cautious attitude to ultrasound.
However, it is still necessary to conduct it. The first study is conducted to make sure that the pregnancy is developing in the uterus, and not in the tube or ovary. The second study helps to determine where and how the placenta is located, how the fetus is developing, whether its development corresponds to the gestational age, whether it has frozen, whether the fetus has gross congenital malformations, whether you are having twins, etc. The third study is a control of the second (fetal parameters are examined). During it, it is usually possible to determine the sex of the future child. Particularly experienced and talented ultrasound specialists can use a sensor to "display" the baby's face on the monitor screen and delight the future dad (if he is present in the office) with the words: "Yes, he is the spitting image of his dad!!!"