However, the screening tests that are offered through the NHS to check whether your baby is at higher risk of conditions such as Down’s syndrome can only be done at specific times in your pregnancy.
The ‘combined test’ uses three factors to check risk:
- a blood sample from you that measures two proteins
- an ultrasound scan ( nuchal translucency scan) of your baby that needs to happen between 11 weeks and 14 weeks of pregnancy
- your age.
During the scan the sonographer measures the fluid at the back of the baby’s neck. This measurement will change after 14 weeks plus one day.
If you have your booking appointment later in your pregnancy, your midwife can offer you the ‘quadruple test’. This test uses two factors to check risk:
- a blood test that can be done from 14 weeks up until 20 weeks of pregnancy and that measures four proteins
- your age.
There is another screening test that is not available through the NHS but is offered in private clinics – it costs between £400 and £900. This is called the non-invasive prenatal screening test (NIPT). This test looks at the risk of Down’s syndrome and some other conditions and can be carried out from 10 weeks until the end of pregnancy.
It uses two factors to check risk:
- an ultrasound scan to confirm the accurate dating of your pregnancy
- a blood test from you – this examines the small amount of your baby’s fetal cells that can be found in your blood.
The result of this test is said to be highly accurate, but it does give a small number (0.3 percent) of false positives. A false positive is where it tells you that your baby has Down’s but this is not true. If you get a positive result, you’ll still need a diagnostic test, such as CVS or amniocentesis, to confirm the result for certain.
If you are interested in having the test at a private clinic, the charity Antenatal Results and Choices (ARC) suggests you check that the clinic has a clear link with an NHS unit. This means that there will be a co-ordinated care pathway in place if your test result is positive.
1. NHS Choices [accessed 10 February 2015] ‘Screening for Down’s syndrome’ http://www.nhs.uk/conditions/pregnancy-and-baby/pages/screening-amniocentesis-downs-syndrome.aspx
2. Antenatal Results and Choices [accessed 10 February 2015] ‘Non-Invasive Prenatal Testing (NIPT)’ http://www.arc-uk.org/tests-explained/non-invasive-prenatal-testing-nipt .
3. NHS RAPID Project [accessed 10 February 2015] ‘What is NIPT for Down syndrome?’ http://www.rapid.nhs.uk/guides-to-nipd-nipt/nipt-for-down-syndrome/.Hide details
ℹLast reviewed on April 1st, 2014. Next review date April 1st, 2017.