If you book with your midwife between 14 and 20 weeks of pregnancy you will be offered the “Quadruple Test”. This involves your midwife taking a blood sample which can be taken from 15 to 20 weeks of pregnancy but ideally at around 16 weeks. You will be offered a scan before the blood test so we know exactly how many weeks pregnant you are. Four substances (proteins) in your blood are measured in the laboratory and these are used to calculate the risk of your baby having Down’s syndrome. A result will not be given unless both the scan and the blood test are completed.
The quadruple test is accurate in eight out of 10 (80%) Down’s syndrome affected pregnancies. This is called the detection rate. Four to five in a 100 women (4-5%) will be told they are at increased risk when actually their baby is unaffected. This is called a false positive rate.
If you have a low risk result from this blood test then you will get the result by letter within two weeks of having the test and no further tests will be required. You will still be offered the 20 week scan.
If you have a risk that is one in 200 (0.5%) or higher you will be contacted by a specialist midwife (usually by telephone) within three working days to discuss the result so you can decide whether you would like a further test to find out for certain whether your baby has Down’s syndrome or not.
For further information please ask your community midwife.