Thousands of infertile couples who repeatedly undergo IVF treatment in the hope of having a baby could soon benefit from a scientific breakthrough that promises a radical increase in the chances of a successful pregnancy.
Scientists believe they have found a simple and efficient way of selecting the best human IVF embryos that are likely to result in viable pregnancies and the birth of healthy babies.
The breakthrough could end the physical and psychological trauma that results from failed attempts at IVF treatment, which many infertile couples suffer as a result of doctors unwittingly choosing unviable embryos for implantation into the womb.
It could also end the high-risk strategy of transplanting more than one IVF embryo, which can result in multiple births and the the risky "selective reduction" of spare embryos.
In a landmark study, US scientists have identified three key features in two-day-old IVF embryos that will give fertility doctors a greater-than 90 per cent chance of picking the right embryos. "The detection of viable IVF embryos has been an historic problem ever since the first IVF birth in 1978," said Renee Reijo Pera of Stanford University Medical Centre in California, where the research was carried out.
"As a result of this, we should be able to transfer fewer embryos into the womb and to transfer them earlier on in development which should prevent many adverse outcomes."
The current success rate of IVF treatment depends on the age and health of the couple, as well as the fertility clinic, but typically only between 25 and 35 per cent of women succeed in giving birth to a healthy baby. Professor Reijo Pera said she believes the new technique could boost this success rate to between 50 and 75 per cent.
The technique, which uses an automated method of monitoring the development of IVF embryos in the first couple of days after fertilisation, has already received venture capital funding and the first clinical trials are being planned, Professor Reijo Pera said.
The pioneering study, published in the journal Nature Biotechnology, was possible because the researchers had access to 242 spare IVF embryos that had been frozen within 24 hours of the eggs being fertilised.
The scientists allowed each embryo to continue growing for a few days further while recording every detail of their development with time-lapse photography, as well as monitoring the expression of their genes.
Of the 242 embryos, only 100 went on to develop into normal-looking blastocysts, the stage at about five or six days when the embryo becomes a fluid-filled, microscopic ball of about 100 cells. This is about the same proportion that would be expected in normal pregnancies, the scientists said.
IVF doctors usually transplant embryos before the blastocyst stage because of the difficulty of culturing embryos until this later stage of development, but ideally doctors would like to identify which embryos will become blastocysts.
The time-lapse video images enabled the research team to pinpoint three key stages in the development that would predict with 93 per cent accuracy the chances of an embryo becoming a blastocyst.
Tony Rutherford, an IVF specialist at Leeds University and the chairman of the British Fertility Society, said that anything that allows doctors to choose the right embryos in the first two or three days would increase IVF success rates.
"This is a very detailed study of a large number of human embryos. It is an important development, but the proof of concept will be if they can develop the video equipment to allow us to do this in practice," he said.
Case study: 'Odds are stacked against you at the moment'
Marion De, 40, has endured five rounds of IVF treatment with her husband, Partha, 44
There is such an element of luck in IVF in terms of which embryos they can put back in, so the odds are stacked against you. After two rounds of IVF in 2004, I was getting really peeved and could feel the clock ticking. But I was unwilling to give up because I couldn't accept it was happening to us.
We went to see a specialist who diagnosed me with endometriosis, a problem with cells around the womb. I had surgery and eventually doctors thought I'd started the menopause. I was absolutely devastated.
After another failure I thought it was the end of the road, but things changed and when fertilised eggs were put back in the fifth time, one produced our daughter, Eisla, who's now 21 months. We've spent about £50,000 on treatments but it has been worth it. I have since conceived another daughter through IVF, Iona.