You may have concerns about the safety of ultrasound for your growing baby, and while the majority of studies indicate that limited use of ultrasound scans during pregnancy won’t hurt a baby, it’s understandable to be a little apprehensive about getting those fuzzy pictures before he or she is born. But do you really need to worry?

How ultrasound works

Ultrasound sends high frequency sound waves through the body to glimpse the soft tissues and organs beneath them. That makes it especially good for observing fetal development, as the sonographer will get a good look at how the baby’s organs are growing. It makes it much easier to diagnose birth defects early, including some that may be able to be addressed before your baby is born

Why ultrasound could be harmful

The main concern with ultrasound is that the sound waves carry energy into the fetus, and that energy can heat up the tissues in your growing baby. And, unfortunately, there’s no definitive answer on what that heat could do to your baby’s developing body. The possibility exists that some ill effects may occur when ultrasound is used inappropriately.

2D scanning uses a low intensity of ultrasound spread over a large area, which causes minimal heating. The amniotic fluid around your baby and any movements it makes helps to spread any heat.

3D and 4D scans are usually only available in private clinics. 3D ultrasound converts sections of 2D images into a 3D picture. So the power intensity is the same as it is for 2D scanning over a few seconds. 4D ultrasound provides moving images as a video and has a higher power output than 2D ultrasound. Therefore, doctors advise against having a 4D scan in the first half of your pregnancy. That’s because in the earlier weeks your baby is smaller and less active, meaning the heat from a more powerful scan will be less easy to dissipate.

Using ultrasound safely

Despite the very slight possibility of risks, most experts agree that medically necessary ultrasounds are nothing to worry about. Ultrasound has an extremely good safety record and the fact that antenatal ultrasounds have been used for several decades without any apparent ill effect is promising. The evidence that ultrasound may cause left-handedness comes from a few animal and human studies; these are viewed as inconclusive by the Health Protection Agency.

Despite that, experts recommend that you have ultrasound scans only when medically necessary.

Ultrasounds at some private clinics, administered by a technician of unknown training using a machine of unknown calibration and safety, done for an unknown duration of time, in order to get a picture of a fetus’ face, may be considered risky.

The benefit of an ultrasound scan, whether medically necessary or for reassurance to alleviate anxiety, should always outweigh any possible risk; this principle is firmly upheld at Somerset Early Scans.

The staff at Somerset Early Scans are all highly trained clinicians and sonographers, who follow guidelines set by The British Medical Ultrasound Society (BMUS) and adhere strictly to the ALARA (As Low As Reasonably Achievable) principle.

Ultrasound equipment should only be used by people who are fully trained in its safe and proper operation; staff must have an appreciation of the potential thermal and mechanical bio-effects of ultrasound and demonstrate a full awareness of equipment settings. They have a good understanding of the effects of machine settings on power levels. Doppler (which is used to look at blood flow) is never used in early pregnancy when your baby is still developing, particularly with a vaginal probe. However a standard 2D vaginal scan is perfectly safe for you and your baby and this is the standard offering for an early scan of less than 8 weeks.

The ultrasound equipment at Somerset Early Scans is tested weekly, and there is a Quality Assurance programme in place. QA is an essential part of safely managing all imaging equipment, and is a key element in ensuring compliance with relevant guidance and legislation (Dudley and Woolley, A multicentre survey of the condition of ultrasound probes. Ultrasound 2016).

Regular audit is also undertaken to ensure consistent high standards, not only of equipment, but cleanliness and infection control, and scan quality.

Examination times are kept as short as is necessary to produce a useful diagnostic result, and the sonographer always aims to stay within the BMUS recommended scan times (especially for obstetric examinations).

The benefits of ultrasound scans in monitoring pregnancies, and relieving anxious parents, far outweighs any potential risks.

For more information, please read Detailed guidelines for the safe use of diagnostic ultrasound equipment on the BMUS website (

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