Test can screen for Down’s syndrome
The serum test looks for four molecular “markers” in a woman’s blood stream during the second three months of pregnancy.
Although offered to some extent in Britain, it is not yet the standard method of detecting women at risk of Down’s syndrome.
Results from the five-year, 46,139-woman study, reported in the Lancet medical journal, showed that the quadruple test was far more effective than screening based on maternal age alone.
It was also substantially better than the double test, which looks for two markers.
Professor Nicholas Wald, from the Wolfson Institute of Preventive Medicine at St Bartholomew’s Hospital, London, who led the study, said: “These results confirm the value of early second trimester serum screening over screening by use of maternal age alone, in contradiction to recent opinion, and lend support to the decision to offer serum screening to all pregnant women.
“The study also confirms that in the second trimester the quadruple test is sufficiently more effective than the double or triple tests that it should be regarded as the test of choice at this time of pregnancy.”
Screening for Down’s syndrome is widely practised throughout the world early in the second trimester of pregnancy, between weeks 14 and 22.
Women identified as being at high risk are given a definitive invasive diagnostic test, such as amniocentesis which removes foetal cells using a probe passed through the abdomen.
Before the blood tests became available it was assumed that any woman aged 35 or over was at risk of having a Down’s syndrome baby.
The study showed an 81% detection rate when the quadruple test was used, with a false positive rate of 7%.
Of 88 Down’s syndrome pregnancies, a total of 71 were detected.
Relying on maternal age alone led to just 51% of cases being detected, with a false positive rate of 14%.
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