"Early ultrasound" refers to a medical procedure that uses sound waves to create pictures of the inside of the body. It is done in the early stages of pregnancy to check the health and growth of the baby. Full definition
Sex selection was a dim possibility, indeed, because early ultrasound machines were nothing like those available today. (scientificamerican.com)
We've got early ultrasound photos where you can see everyone all in one photo to photos later in pregnancy with only parts together and separately. (verywellfamily.com)
But it can be difficult to draw conclusions based on a single early ultrasound. (verywellfamily.com)