Ultrasound scans during pregnancy

An ultrasound scan (sonogram) uses sound waves that bounce off solid objects to create two-dimensional black and white images on a screen. It's completely safe for you and your baby.

Scans are mainly done to give your midwife and doctor information about how your baby's growing and developing.

Three-dimensional (3D) and colour scans aren’t routinely used in the NHS.

When will I have an ultrasound scan?

You should be offered at least 2 scans:

You might also be offered a nuchal translucency scan (NT) at your early pregnancy scan to to find out how likely it is your baby may have either Down’s syndrome, Edwards' syndrome or Patau's syndrome.

You can choose not to have these scans – the decision's yours.

What your ultrasound scan can show

Your scan can show:

  • your baby’s size, which is important for finding out when they’re due to arrive
  • your baby’s heartbeat
  • the way your baby's lying in your womb, which is important when you give birth
  • whether you’re having twins or more
  • how your baby’s organs and bones are developing, including their spine
  • where your placenta's lying - If it’s low down or lying across your cervix towards the end of your pregnancy, it can affect how your baby needs to be delivered

The scan can also show some health conditions or chromosomal conditions, but it’s not always possible to see them.

Finding out the sex of your baby is not the purpose of screening unless there’s a medical reason for doing so. Often it’s impossible to tell during an ultrasound examination because of the position of your baby. It’s not completely reliable and can sometimes be wrong.