PRO-LIFE campaigners have criticised a Scottish fertility clinic for introducing a screening test that checks for genetic abnormalities before eggs are implanted into a woman.

The Glasgow Centre for Reproductive Medicine (GCRM), which claims the pre-implantation genetic screening (PGS) is a first in Scotland, said it will improve the chances of the eggs going on to create a healthy baby.

Three-quarters of failed IVF attempts are thought to be a result of damaged eggs, so experts say this procedure, which allows doctors to identify which eggs are normal or abnormal, and therefore which are the best ones for implantation, can double the chance of IVF success for older women.

But the move by the private clinic prompted concerns from opponents of the practice who labelled it "factory-like quality control" and suggested it was the gateway to creating "designer" babies.

Peter Kearney, spokesman for the Catholic Church in Scotland, said: "Each and every human has his or her own natural life span, be it seven weeks or 70 years. That life span is not for another to decide.

"In some ways IVF is a reflection of the desire to have children and the desire to wish the best for our children, including good health. However, the problem with this procedure is that once created, human lives deemed unacceptable are simply ended."

SPUC (Society for the Protection of Unborn Children) Scotland, which said its aim is to "affirm and defend the existence and value of human life from the moment of conception", also spoke out against the process.

A spokesman said: "Even if egg-screening helps to increase the number of births following IVF, it will still be the case that the vast majority of embryos created in the laboratory will not be born.

"IVF demeans human dignity by reducing procreation to quality-controlled, factory-like production. Doctors should instead be pursuing the far more successful ethical alternatives to IVF."

The new test involves the removal of "polar bodies" from the eggs collected for IVF. These are tiny cells containing the chromosomes discarded by the egg as it makes way for those that will be delivered by the sperm.

The polar bodies are sent to Oxford, where they are tested to ensure they have the correct number of chromosomes.

The patient's eggs remain at the GCRM in Glasgow until the results of the tests. Staff are then able to identify which eggs are normal or abnormal, and therefore which are the best ones for implantation.

The test will be offered to GCRM patients for around £2350.

The clinic hopes it will be especially useful to older women, whose eggs are more likely to be damaged, and to couples who have a history of repeated miscarriage or failed IVF attempts.

Dr Marco Gaudoin, of GMRC, insisted last night that the only embryos that would be destroyed would be those that would have no chance of being successful.

He said: "We do in IVF destroy a lot of embryos, but in our view they are destroyed because there is not a chance of producing a baby."

Dr Dagan Wells, the geneticist whose company Reprogenetics UK helped develop the test, called comparative genomic hybridisation, said the process was an important method of improving success rates in IVF.

Professor Sheila McLean, director of the Institute of Law and Ethics at Glasgow University, said that while such IVF treatments can be distressing for opponents of the process, there is generally no ethical concern.

She said: "It [the process] will be done for what are proper medical reasons, and in this country we have standard guidelines that will have to be followed."