12-week scan

12 week scan shows baby with thumbs upThere are two routine scans in pregnancy and the first is called the 12-week or dating scan. This is because one of the things it tests is the exact gestation, giving a better idea of your baby's estimated due date (EDD).

The dating scan is usually done at some point between 8 weeks and 14 weeks. NICE recommends it's done between 10 weeks and 13 weeks.

What happens during the scan?

Before the scan you will be asked to drink a lot of water and have a full bladder, as this puts the uterus in a better position to be scanned. This can be a bit of an uncomfortable challenge if your scanning clinic has particularly long waiting times.

When it comes to the actual scan you will lie on your back and then some sticky, clear jelly will be rubbed over your abdomen.

The ultrasound's transducer - a hand-held device - is moved over your belly and bounces high-frequency sound waves off your belly to create a picture on the monitor. Don't worry, it's painless and there's no evidence it harms you or your baby.

The clarity of the picture depends on a number of things, for instance if you have any abdominal scarring the picture may not be as clear.

You will be able to watch the monitor and see the first pictures of your baby, which is an extraordinary moment, whether its your first or final baby.

It may not be immediately obvious which parts of your baby you're looking at, but the sonographer will be able to help you work it out. He or she may need to prod your belly a bit to 'encourage' the baby into a suitable position.

The ultrasound scan is a great milestone in your pregnancy and it is great to share it with your partner. You may have had reservations about the test and be worried about the results, so it can be a great comfort to see your baby on screen and have the reassurance that everything is all right.

Some hospitals will sell you a copy of your scan image so you can go and show everyone the very first picture of your sproglet-to-be.

What does the 12-week scan show?

  • Age and size: your baby will be measured and the exact stage of pregnancy will be calculated from the measurement made from crown to rump. This will give you a more precise estimated due date.
  • The number of babies: are you expecting one baby, twins or (gulp) more?
  • Development and growth: the sonographer will check your baby's limbs and spine for any visible abnormalities. They will look at the head, limbs, feet, heartbeat and whether the major organs are developing as they should.
  • The health of the placenta and its position, which may have implications for later in the pregnancy.

You may also be asked whether you want a nuchal translucency test carried out. This is a measurement of the amount of fluid at the base of the neck and it can indicate a higher risk of Down's syndrome. Not all areas offer this test as routine. 

The pregnancy screening tests and scans you'll be offered vary between different parts of the UK, so ask your midwife or GP what's available at the hospitals in your area.

What Mumsnetters say about the dating scan 

  • Such a fantastic feeling, I carried my little pic everywhere with me and spoke to it! (Seemed more 'real' than thinking was actually in my tummy somehow.) Beatofthedrum
  • At my 12-week scans for my son and daughter they were both asleep in a little ball and I had to jump about so the midwife could get a good look. Cbear6
  • Having to drink all that bl**dy water before a scan only to find there's a delay before your appointment and then you feel like you're going to explode. I'll never forget one nurse asking me (when they were nearly 30 mins over time), 'Do you think you could just pop to the loo and let just a little bit out?' Errrr - NO! JonesTheSteam
  • If you have a toddler in tow, take plenty of activities/ treats for them plus nappies etc, the waits can seem endless to a two year old. And don't (as I did - twice) get all the way there and realise you've left your notes at home. Haley


Last updated: over 1 year ago