Ultrasound scans have been used in pregnancy for decades, and nobody has found them to be harmful if carried out correctly.
To be on the safe side, there are clear guidelines on the use of scans in pregnancy, which your sonographer will follow.
Studies have found no link between ultrasound and birth weight, childhood cancers, dyslexia, eyesight, or hearing.
Most experts agree that scans should only be performed by a qualified healthcare professional. Even then, scans are only recommended when there's a clear medical reason, such as checking that your baby's developing normally. This is why you'll probably only have a few scans during your pregnancy.