Cytocell, a biotech firm from Oxfordshire, UK, has developed a simple, safe and reliable test that uses foetal blood cells that leak through the placenta into the mother's circulation, to detect genetic abnormalities. The technique may eventually replace amniocentesis, which presents a one-in-200 chance of a miscarriage.

But the test only makes use of samples obtained from after 16 weeks of pregnancy, and the foetal cells have to be cultured for three weeks. Cytocell is coming up with another technique called 'fluorescence in situ hybridisation' that could provide faster results.