The world's first pregnancy using a new technique for screening eggs has been announced by a fertility clinic in Nottingham.
Scientists have tested the eggs for abnormalities which cause IVF to fail.
The team at the CARE Fertility clinic have found a way of extracting a "spare" set of chromosomes inside the egg and rapidly analysing them.
They believe it has the potential to significantly improve couples' chances of having successful treatment.
Perhaps the main reason why two out of three women fail at each attempt at IVF is due to chromosomal abnormalities in their eggs.
There should be just 23 chromosomes in the egg which contain the woman's share of the genetic code - the other half come from the sperm after fertilisation.
The spare chromosomes in the egg are found near its edge in what is known as the polar body.
The new technique is called array CGH (Comparative Genomic Hybridization).
A laser cuts a hole in the edge of the egg and then, using a pipette, the polar body is sucked out.
The chromosomes inside the polar body should be a mirror image of those left in the egg.
So by analysing what is in the polar body, scientists can work out what is left behind in the egg, without disturbing it.
If they find, for example, that there is a chromosome missing from the egg, then any subsequent embryo will fail, even though it looks healthy down the microscope.
If they find an extra chromosome then it could lead to a miscarriage or a pregnancy with an inherited genetic disorder.
Two years ago US scientists announced that 18 women had given birth after having their eggs screened with CGH, with another eight pregnant.
But in those cases the subsequent embryos had to be frozen and re-implanted later, because the results of the screening took five days.
A breakthrough with the array CGH technique is that the results come back within 24 hours so IVF can be done in the same cycle of treatment.
It also removes the moral and religious objections some couples feel about creating and testing embryos which may be destroyed.
The first woman in the world to be successfully treated wishes to remain anonymous.
But the CARE clinic say she is 41, and had thirteen previous attempts at IVF and three miscarriages. She is now six months pregnant.
Could benefit many
Dr Simon Fishel, director of the CARE fertility group, believes it could help many more women.
He said: "We know that at least half the eggs and embryos produced are wasted due to chromosomal abnormalities.
"If we could chose those with normal chromosomes logic tells us we double the chances of pregnancy and that's what we hope."
Dr Fishel also says that it could help reduce the number of twins and triplets associated with fertility treatment.
"In this country we have to reduce the incidence of multiple pregnancy and there's a big drive to put a single embryo back.
"That could reduce all women's chances of pregnancy but not if we choose the embryo that is most viable and has normal chromosomes.
"Ultimately we could reach the holy grail of one cycle of IVF, one egg, one embryo and one baby."
Nicole Klieff would certainly welcome that.
She underwent fertility treatment for nine years and spent £65,000.
In that time she had six failed cycles of IVF and two miscarriages.
On her seventh attempt, her daughter Lauren was born, who is now four years old.
Nicole says it took a lot out of her, physically and emotionally.
She said: "The only way I can describe it is as a roller-coaster ride.
"Your emotions are up and down and you need to have a great amount of patience, endurance and mental strength to carry it through."
Nicole has written a book about her experiences and says that for couples with fertility problems, any significant improvement in success rates would be tremendous.
She said: "When you are infertile you want to find out why am I infertile and how long is this going on for and how much is it going to cost me or can I get the medical help that I wish to have."
Around 35,000 women undergo IVF in the UK each year and just one in three cycles is successful.
More work needed
But it is far too early to know if array CGH is going to transform success rates.
Stuart Lavery, a consultant gynaecologist and director of IVF at Hammersmith Hospital in London, said: "We need further research in this area so questions of reliability, efficacy and safety can be fully answered."
That is likely to take some years.
Tony Rutherford, chair of the British Fertility Society, described the research as exciting and promising - but also urged caution.
He said: "The widespread use of this technology should await the outcome of such research to ensure we know which patients might benefit.
"All too often we see ground-breaking news about techniques that seem to offer great hope, but fail to live up to expectations when applied in widespread clinical practice."