Pregnancy ultrasound scans

Everything you need to know about these very important scans

Seeing your unborn baby on an ultrasound scan for the first time is an amazing experience and one that you’ll treasure forever.

It’s so exciting to see your little one kicking around and sucking their thumb (yes really!) but there’s also some really important science behind having scans during your pregnancy. Here’s why you have them, how often you’ll need them and what to expect.

At a glance

  • You will generally be offered two scans by the NHS
  • Ultrasound scans are used to give you a more precise due date
  • They can detect abnormalities in your baby

What is an ultrasound and why do I need one?

Ultrasounds use sound waves to build a picture of the baby in the womb and are completely painless – although be warned, the gentle pressing of the sonographer on your belly, plus all the water you’ll need to drink, may mean you need to wee! 

They are one of the only ways your doctor can see and make sure your baby’s organs are developing correctly, detect a heartbeat and also to help with potential abnormalities, such as Down’s Syndrome (more on this later) and Spina Bifida. 

Other reasons why an ultrasound is given include: 

  • To find the position of your placenta
  • To check whether you’ve been blessed with more than one baby
  • Find out why you may be bleeding
  • To give you a more precise due date
  • To detect an ectopic pregnancy. 
  • How many ultrasounds will I have?

Ultrasounds have no known side effects on you and your soon-to-be new arrival and can be carried out at any stage of pregnancy. 
If your pregnancy is going normally you’ll be offered two routine scans through the NHS. 

If you are found to be expecting twins or more, or your little one isn’t developing as doctors would like, you will be given as many as the experts think you need. 

The first time you get to meet your baby on the screen 

Unless you choose to pay for a private scan, the first time you’ll see your baby will be at around 12 weeks. Commonly known as a ‘dating scan’, this first appointment – or to give it its proper name, the nuchal translucency scan - will give you a better estimation of your due date. 

You can work out an approximate due date before your first scan by using our pregnancy due date calculator on 

During the scan the sonographer will also check whether your little one is at a lower or higher risk of being born with Down’s Syndrome.

This is done by measuring the thickness of the nuchal translucency (a pocket of fluid) at the back of your baby's neck. These measurements are then combined with a blood test to check the levels of your protein.  Through this combination doctors can work out whether you’re at a high or low risk of having a little one with Down’s and discuss this further with you. 

If you are found to be at a higher risk then you may want to speak to someone such as the Down’s Syndrome Association.

The second time you get to see your little one 

The second scan usually takes place between 18 and 21 weeks. It's called the anomaly scan because it checks whether your little one’s organs and bones are developing as they should.

Team pink or blue?

During the 20 week scan you may be given the option to find out whether you’re having a boy or girl (some hospitals have a policy of not offering this, so do check beforehand). 

If you want to find out the sex of your baby, tell the sonographer at the beginning of your scan. If the hospital offers this and your little one is co-operating – for example not lying in an awkward position – then they will tell you. 

Even if you choose not to find out, be warned little boys do sometimes have a habit of er, showing off, so you may end up finding out accidentally. 

What happens during an ultrasound scan in pregnancy?

You’ll be asked to drink around a litre of water or squash about 30 minutes before your appointment – remember you won’t be able to have a wee before the scan as you’ll need a full bladder to give a better picture of your little one. However, keeping your legs crossed is worth it when you see your baby on the screen – we promise. 

Once it’s your turn you’ll be asked to lie on your back while the sonographer puts some lubricating gel on your stomach – it can be cold so brace yourself! 
A small device is then passed backwards and forwards over your skin, and high-frequency sound is beamed through your abdomen into the womb. The sound is reflected back and creates a picture, which is shown on a TV screen. 

Top tip

Take plenty of change with you when you go for your scan. You’ll usually be able to buy pictures of baby, with some hospitals offering this via a machine. 

It’s your choice 

The dating and anomaly scans are offered to every pregnant woman, but you don't have to accept them. If you choose not to have these then you’ll be given the chance to discuss your baby’s development with your doctor. 

At a glance

  • You will generally be offered two scans by the NHS
  • Ultrasound scans are used to give you a more precise due date
  • They can detect abnormalities in your baby
It was so exciting seeing my little one on the screen for the first time

Pregnancy ultrasound scans

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