Chorion villus sampling, that wonder prenatal diagnostic test that supposedly avoided the problems of amniocentesis, could be causing severe limb deformities, particularly when carried out very early in pregnancy.

In 289 pregnancies in which CVS was carried out at Oxford, five babies with severe limb abnormalities resulted. These included arms without hands, limbs ending just below the elbow and hands without fingers.

"The spectre of abnormalities present in these five cases are consistent with incomplete rather than abnormal morphogenesis, in which an insult disrupts the development of a normal embryo or foetus," said the authors, from John Radcliffe Maternity Hospital in Oxford.

Translated from medicalese, that means that instead of some sort of inherent defect, these deformities were caused by the growth process being disturbed by a foreign agent, in this case probably the CVS.

If CVS was responsible, the Oxford sampling showed that the procedure raises the risk of such deformities to one in six, compared to an ordinary risk of l per 175,000.

As a result of these findings, Oxford now has put a halt to any further procedures until it determines whether CVS can ever be carried out safely.

In CVS, a sample of chorion villus is taken from the womb by way of a spinal needle guided by ultrasound.

CVS was hailed as a breakthrough technique for older pregnant women because it supposedly could detect foetal abnormalities such as Down's Syndrome far earlier than amniocentesis, which must be conducted in the 16th week, with results determined three weeks later. Women who decided to have abortions based on the results of their studies had to go through a late term termination, whereas CVS was thought to offer women the possibility of an early abortion.