Women undergoing fertility treatment could more than double their chances of having a baby with a new technique for detecting chromosome abnormalities in their eggs, scientists said yesterday.
The procedure – developed in Britain – has already enabled a 41-year-old woman with a history of miscarriages and failed IVF attempts to become pregnant with her first child. A leading fertility specialist said it was a fast and accurate method of detecting changes to the 23 chromosomes within the human egg that are implicated in miscarriages and birth defects.
"We are likely to reduce the number of miscarriages, increase the number of implantations into the womb and increase the number of live births with this technology," said Simon Fishel, managing director of Care Fertility, an IVF centre in Sheffield. "We now have a technology that can examine all chromosomes from either an egg or an embryo."
About half of the eggs produced by women carry chromosome abnormalities that can affect the chances of giving birth to a healthy baby. For women aged 40 or more, this rises to 75 per cent of eggs.
Dr Fishel and colleagues used the test on nine eggs extracted from the 41-year-old woman, who had previously undergone 13 cycles of failed IVF treatment. Even without her history of failed IVF attempts, the woman's chances of having a baby would be less than 7 per cent, he said. The new chromosome test showed that just two of her nine eggs were normal. These were subsequently implanted into her womb after being fertilised and she is now more than six months pregnant with a single child.
The technique, which costs £1,950 and is not offered on the NHS, involves extracting the "spare set" of chromosomes ejected from the egg in a structure called the polar body. Scientists then extract the polar body's DNA and test it for chromosome changes without any interference to the DNA of the egg itself, Dr Fishel said. Only eggs that prove to have a normal complement of chromosomes are selected for implantation into the womb. This significantly cut the risk of failed implantation or miscarriage – a trial doubled implantation rates, Dr Fishel said.
The latest version of the test has been automated with the result that it takes no more than 48 hours to complete, so the IVF embryos do not need to be frozen before implantation.
However, the British Fertility Society said that further research and clinical trials were needed before the new test is offered widely to couples undergoing IVF treatment.
50 per cent: The proportion of eggs produced by women that carry chromosome abnormalities
75 per cent: The proportion with chromosome abnormalities for women over 40Reuse content