Your 12-week dating scan: what to expect
For many people the dating scan is the first proper glimpse of their baby, and the first real "this is happening" moment. Here is what the scan is for, what actually happens on the day, and why it might tweak your due date.
What the scan is for
The dating scan, usually offered between 8 and 14 weeks, does a few key jobs at once. It confirms how many weeks pregnant you are and works out your estimated due date, checks how many babies you are carrying, and looks at your baby's early development. It is also when you can choose to have screening for certain conditions.
When it happens
Most people have their dating scan at around 12 weeks, after their booking appointment with the midwife. If you are not sure of your dates, our due date calculator gives you an estimate in the meantime, and the scan will refine it.
What happens on the day
The scan is usually done across your tummy. You will be asked to come with a full bladder, which helps give a clearer picture, so it is worth following the instructions on your appointment letter. A sonographer spreads a little gel on your tummy and moves a probe across it, and your baby appears on the screen. It takes around 20 to 30 minutes, and most units can print a photo for a small fee.
Screening you may be offered
Around this time you will be offered screening for conditions including Down's syndrome. One part of this is the combined test, which uses a measurement from the scan along with a blood test. Screening is always your choice, and your midwife will explain what it does and does not tell you so you can decide what is right for you.
Why your due date can change
The scan measures your baby and uses that to estimate your due date, which is often more accurate than dating from your last period, especially if your cycles are irregular. If the scan date and your period date disagree, the scan normally takes priority, so do not be surprised if your due date shifts by a few days. Our guide to how due dates are calculated explains why.
Frequently asked questions
Can I find out the sex at the 12-week scan?
No, it is too early to tell reliably. That usually comes at the 20-week anomaly scan, if your unit offers it and you want to know.
Do I need a full bladder?
Usually yes, as it improves the view. Follow the instructions on your appointment letter.
Can my partner come?
In most cases yes, though policies vary, so check with your unit beforehand.
The bottom line
The 12-week dating scan confirms your due date, checks how many babies you are expecting and how they are developing, and offers screening if you want it. Come with a full bladder, expect it to take around half an hour, and do not be thrown if your due date moves slightly, the scan is simply the more accurate measure.
Sources
- NHS, The 12-week scan and screening in pregnancy.
Read next: Pregnancy week by week · How due dates are calculated.
This article is general information, not medical advice. Your midwife and sonographer will guide you through your own care. See nhs.uk/pregnancy for trusted guidance.