Testing the “energy supply” in an embryo could improve the odds of having a baby through IVF, University of Oxford researchers say.
They analysed the activity of microscopic power stations called mitochondria in 111 embryos.
The data, being presented at a conference, found a 0% pregnancy rate if mitochondrial activity was high.
Experts said the results were an exciting development that may boost IVF success rates.
There is huge effort being put into improving IVF – for women under the age of 35, only about of third of cycles result in a baby
One approach is to select the healthiest embryo to implant into a woman’s womb from the multiple embryos made during IVF.
Visibly inspecting the embryos and checking they have the correct set of chromosomes, or genetic information, from both mother and father increase success rates.
But even when embryos appear normal, many fail to implant.
The Oxford team added a mitochondrial inspection to the mix and tested levels of mitochondrial DNA in five-day-old embryos.
Data, presented at the European Society of Human Reproduction and Embryology, showed only 78 of the 111 embryos successfully implanted to result in pregnancy.
It also showed, 76% of embryos that looked physically normal, had normal chromosomes and normal mitochondrial activity implanted.
But 0% of embryos implanted if they had abnormal mitochondria, even though everything else looked healthy.
Dr Elipda Fragouli, one of the researchers, told the BBC News website: “It is exciting, it is something interesting, something new and hopefully we will be able to use it clinically.”
Fellow researcher Prof Dagan Wells said: “A relatively small number of embryos – around 10% – have this problem, but anything that can help us with embryo selection has to be a good thing.”
He hopes better testing of embryos will avoid the “emotional rollercoaster” of repeatedly failing to get pregnant.
But the researchers warn it is only a test and cannot improve the embryos if they are all of poor quality.
The test is already being offered in the US, and the fertility regulator, the Human Fertilisation and Embryology Authority, is considering whether it should be allowed in the UK.
Prof Nick Macklon, from the University of Southampton, told the BBC News website: “I think it’s an exciting scientific development, it provides a window on a aspect of embryo function that we haven’t been able to look at before.”
But he added: “It may help us select the best embryo with the best chance, but these are early days and I think it is something that may or may not be added to our tools for assessing embryo quality.”
The mitochondria test would add about £200 ($ 265) to the cost of current testing, but the researchers believe that eventually it could be done at no extra cost.
Prof Adam Balen, the head of the British Fertility Society, said the study backed the “quiet embryo hypothesis” as those with very active metabolisms and high mitochondrial activity were likely to be responding to some unseen stress.
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