London - Fertility experts have found a new way to identify embryos that will implant in the womb, which could boost IVF success rates by up to 50 percent.
The presence of high levels of DNA from energy-producing cells in an embryo is a signal that it could fail to implant, according to Oxford University researchers.
But they have discovered a threshold below which embryos are guaranteed to implant.
Lead researcher Dr Elpida Fragouli, of the Nuffield Department of Obstetrics and Gynaecology in Oxford, said the discovery could be a “new independent biomarker of embryo viability”, helping doctors to choose the embryos most likely to result in pregnancy.
Each year, clinics in Britain carry out around 60 000 IVF treatments but many couples remain childless because the embryo fails to implant in the womb. Sometimes this is because the embryo has genetic defects, but it can happen even if it seems to be healthy.
It is thought the new finding may explain around one in three implantation failures.
Dr Fragouli explained that at most IVF clinics 20 to 30 percent of women who have treatment will have a baby.
She said: “We believe that adding this biomarker to the process will increase those rates to 50 or 60 percent. It’s very easy to do, it only takes a couple of hours, and although we haven’t worked out a price yet it will be very cheap, just a few pounds.”
The researchers investigated whether the amount of mitochondrial DNA (mtDNA) – the genetic material in the tiny power packs of cells – affected the chances of an embryo implanting in the womb.
They took biopsies from 392 embryos at the five-day stage of development, when mtDNA levels start rising. They also looked at 87 women aged around 38 at the stage when the embryo was transferred to the womb.
They found healthy embryos capable of implanting had lower levels of mtDNA than those failing to implant. There were also high levels of mtDNA in embryos with genetic defects and those from older women, especially those over 40.
Importantly, they established a threshold of mtDNA below which implantation was certain. Of the healthy embryos that failed to implant, 30 percent had levels of mtDNA above this threshold, while 100 percent of healthy embryos that produced a pregnancy had levels below it.
Dr Fragouli said it was not clear why high levels of mtDNA affect implantation, though they could be a sign the embryo is under stress.
“It suggests there may be a problem, not necessarily in the chromosomes, and extra energy is needed to correct the problem, but it is not really fixable,” she said. - Daily Mail