Screening test would give hope to childless couples

Oct 20 2005

According to new research thousands of childless British couples could greatly improve their chances of having a baby if a test that weeds out faulty embryos were carried out.

The research suggests that such screening would benefit many more women than has generally been thought, and its routine use could transform IVF success rates while preventing risky twin and triplet births.

The procedure, which is known as aneuploidy screening, is already available at eight clinics in Britain, but is officially recommended only for women aged over 35 or who have already endured multiple miscarriages or failed IVF attempts.

Now three American studies, have found compelling evidence that it could also help younger women and newcomers to fertility treatment, as their embryos are almost as susceptible to the defects it is designed to root out. The leaders of the research say the results "rewrite the medical textbooks" about younger women’s fertility.

The screening technique works by removing a single cell from a three-day-old embryo and checking it for aneuploidy, a set of disorders in which an abnormal number of chromosomes triggers miscarriage or genetic conditions such as Down’s syndrome.

These conditions are most common in older women and those with a history of failed pregnancies, and the test is generally limited to such patients. Human Fertilisation and Embryology Authority (HFEA) guidelines state clinics are not expected to use it for anyone else.

However the new research, presented this week at the American Society for Reproductive Medicine conference in Montreal, indicates, that aneuploid embryos are also a frequent problem for younger women.

As many as half the IVF embryos produced by women as young as their mid-twenties are chromosomally abnormal, which means that screening embryos and implanting only those with a good chance of developing normally should be considered for a much wider group.

Jeffrey Nelson, of the Huntington Reproductive Centre in Pasadena, California, who led one of the studies, said the HFEA guidelines are too strict, and the fact that there are young women who have a high rate of abnormalities suggests that the technique should be more in use.

In his research Dr Nelson found that 42 per cent of the eggs collected at his clinic from young donors, with an average age of 25, generated aneuploid embryos.

Paulette Browne, of the Shady Grove Centre in Rockville, Maryland, also found a 50 per cent abnormality rate from egg donors with an average age of 26½.

In a third study, led by Zsolt Peter Nagy, of Reproductive Biology Associates in Atlanta, it was found that two thirds of the embryos were abnormal in IVF patients under 35.

Aneuploidy screening was approved in Britain in 2002, and costs about £2,500 on top of regular IVF costs. It is not generally available on the NHS.