New early Down’s syndrome test more reliable

A new non-invasive blood test that can be given earlier in pregnancy may be more reliable compared to current checks, says researchers.

09:59 11 June 2013

A new test designed to detect if an unborn child is affected with Down’s syndrome is more reliable compared to current checks, says researchers. This is a non-invasive procedure, which involves analyzing the baby’s DNA, which is present in its mother’s blood.

 

Pregnant women are given an ultrasound screen and hormonal analysis between the 11th and 13th weeks of pregnancy to analyse their blood. However, the only definitive tests involved chorionic villus sampling and amniocentesis that carry a risk of miscarriage. 

 

The study,which involved 1,000 pregnant women found that Down’s can be detected using foetal cell free DNA (cfDNA) from a pregnant woman’s blood. The test false positive rate is 0.1per cent, which is lower than the 3.4per cent rate for combined tests. 

 

The authors said: "Screening for trisomy 21 by cfDNA testing contingent on the results of an expanded combined test would retain the advantages of the current method of screening, but with a simultaneous major increase in detection rate and decrease in the rate of invasive testing."