What is the purpose of the dating scan?
The purpose of the dating scan is to check:
- how many weeks pregnant you are and work out your due date (the estimated date of delivery, or EDD)
- whether you're expecting more than 1 baby
- that the baby is growing in the right place
- your baby's development
This scan can detect some health conditions, such as spina bifida.
Does screening for Down's syndrome happen at the dating scan?
This depends on whether you have agreed to have the screening and when the scan takes place. Screening for Down's syndrome will happen at the dating scan if:
- you have agreed to have screening for the condition
- the scan takes place between 10 and 14 weeks of pregnancy
The screening test for Down's syndrome used at this stage of pregnancy is called the "combined test". It involves a blood test and measuring the fluid at the back of the baby's neck (nuchal translucency) with an ultrasound scan. This is sometimes called a nuchal translucency scan.
The nuchal translucency measurement can be taken during the dating scan. If you have agreed to have screening for Down's syndrome, the dating scan and the screening will usually happen at the same time.
Find out more about the combined screening test for Down's syndrome.
You will not be offered the combined screening test if your dating scan happens after 14 weeks. Instead, you will be offered another blood test between 14 and 20 weeks of pregnancy to screen for your chance of having a baby with Down's syndrome. This test is not quite as accurate as the combined test.
Find out more about:
You can also read Screening tests for you and your baby, from Public Health England.