Embryo screening helps woman, 42, become pregnant

An embryo screening technique that could dramatically improve the success rate of fertility treatment for older women and reduce the risk of their having a Down's syndrome baby has produced its first pregnancy in Britain.

A 42-year-old woman who suffered miscarriages and periods of infertility for six years is 10 weeks pregnant, her doctors said yesterday.

The technique, known as aneuploidy screening, examines newly conceived embryos for genetic defects, allowing doctors to weed out those with serious chromosome disorders.

These abnormalities are more common as women become older and are thought to be responsible for many cases of recurrent miscarriage. They may also partly explain why fertility drops so sharply as a woman reaches her late thirties and early forties.

Aneuploidy screening has been available in America and some European countries but was licensed in Britain only from last November.

The woman, who has not been named, had at least two miscarriages in her mid-thirties and in recent years had been unable to become pregnant.

She was treated by CARE at the Park Hospital near Nottingham, one of three clinics licensed to carry out aneuploidy screening.

The test showed that four of six embryos conceived during her IVF treatment had chromosomal abnormalities. Doctors transferred the two healthy embryos into her womb and one began to develop normally.

"Embryo screening was important for us," the woman said. "We were thrilled to know that two embryos were normal."

Dr Simon Fishel, the director of the CARE clinic, said the technique offered hope to women who were finding it difficult to have babies.

Under the rules laid down by the Human Fertilisation and Embryology Authority, his clinic can use the test only on women suffering recurrent miscarriages, those for whom repeated conventional IVF treatment has failed and those over the age of 36.

The test is carried out on an embryo two to three days after conception when it is still a ball of eight cells. One of the cells is removed and its DNA isolated. Researchers use fluorescent DNA probes to identify seven of the most vulnerable chromosomes. The test can show if the embryo has an additional chromosome 21 - the cause of Down's syndrome - or if chromosomes are mixed up.

The clinic has treated 10 couples using the test. Four couples have failed to produce any healthy embryos. Dr Fishel said that between 45 and 70 per cent of embryos produced by older couples had chromosomal disorders.

Because many such embryos would fail to develop, he believes that the test may raise the IVF success rate. However, the removal of a cell from the embryo could reduce its chances of healthy development.

He dismissed accusations that aneuploidy screening was creating "designer babies". He said that pre-implantation screening was more acceptable than an amniocentesis test carried out between the 13th and 18th week of pregnancy.

"Antenatal screening is routinely accepted," he said. "But should a problem arise, couples may face a termination well into pregnancy. Screening an embryo for high risk couples could prevent that happening."

18 June 2003