Technology is now available which could help ease the uncertainty

Dr Lisa Levett, Cytogenetic DNA Services

Although the test is not yet available on the NHS, it is available privately.

The British laboratory which developed the technique is offering the test to women who have been advised by their midwife, GP or consultant to undertake an amniocentesis test.

It can be carried out on women who are between 12 and 34 weeks pregnant.

Approximately one in every 650 foetuses is at risk from Down's syndrome. The risk increases with the age of the mother.

Dr Lisa Levett, director of Cytogenetic DNA Services where the test was pioneered, said the technology could be used to reduce pressure on expectant mothers.

"Expectant mothers who are at risk of genetic birth defects and have been advised to undergo amniocentesis are clearly vulnerable.

"It they then have to wait up to three weeks for test results during this difficult period, the pressure on them and their families can be immense, knowing that they may have to make some very difficult decisions.

"But technology is now available which could help ease the uncertainty."

A spokesman for the National Childbirth Trust said many women underwent amniocentesis tests unnecessarily.

"In many cases, tests are being carried out on women where there is no clinical need.

"In many cases tests are being suggested or are being carried out with no good reason.

"When the test is carried out it does of course cause stress.

"If this 48 hour test proves to be true, it would relieve stress considerably."