Ultrasounds use sound waves to create images of your baby while you are pregnant. When performed by a skilled professional, these scans are very safe for you and your baby. They are also pain-free and you cannot hear the sound waves.
Ultrasound scans can be used for many different purposes, including but not limited to determining the (estimated) due date of your pregnancy, assessing if your baby is developing normally, or looking at the position of the placenta. Some are routine scans, but some are done because your doctor or midwife might be worried about your baby. It is one of the investigations that we can use to ensure the wellbeing of you, your pregnancy and your baby. Your doctor and midwife will discuss with you why they are recommending each ultrasound and you can then choose whether or not to have the scan. If you are concerned about your baby or your pregnancy, you can also discuss with your doctor or midwife whether or not an ultrasound is needed.
Consider reading this site for a bit more information about ultrasounds in pregnancy: https://www.qld.gov.au/health/children/pregnancy/antenatal-information/your-care-during-pregnancy/ultrasounds-during-pregnancy#:~:text=Ultrasounds%20use%20sound%20waves%20to,to%20an%20x%2Dray)