Pregnancy rates at US fertility clinics have risen thanks to a test that checks IVF embryos for abnormalities in the DNA.
According to the scientists from Oxford which helped in developing this test it is able to rise the pregnancy chance of IVF by 10 percent. Increasing the success rate to a maximal 75% among women that are 35 years old.
The test itself does not increase the quality of the embryos but it gives the doctors a tool which helps them find the healthiest embryos among the available ones. Such embryos are of best quality and so they are most likely to produce a healthy pregnancy.
This procedure of pre-implantation genetic screening PGS is already offered by many fertility clinics around the world. It is used to spot the embryos with abnormal amount of chromosomes.
The major cause for the embryos to fail at implanting or to miscarry is precisely the abnormalities in the chromosomes. However even when using PGS which is an expensive procedure costing from 2000 to 3000 pounds, about one third of all the embryos fail to produce a healthy and successful pregnancy.
High levels of DNA in the mitochondria in many embryos which failed to implant was noticed by the researchers from the Oxford Biomedical Research Centre. Hundreds of mitochondria is carried by healthy cells to provide energy.
The leader of the research at Reprogenetics Elpida Fragouli said “Based on our findings we have devised a test whereby a small number of cells, carefully removed from an embryo, can be measured for the amount of mitochondrial DNA present. This will help guide doctors to the IVF embryos with the greatest chance of producing a viable pregnancy.”
Several clinics in the United States are already offering the test called MitoGRade. According to the presentation shown at the American Society for Reproductive Medicine the research done on 100 couples boosted the pregnancy rates to 75% from maximum 65%.
The UK project leader Dagan Wells said “Anything that reduces the number of unsuccessful embryo transfers that patients have to endure will certainly be welcome. This important discovery indicates that mitochondria represent an important piece in the complex jigsaw puzzle that is infertility”
The reasons for the sudden increase of mitochondrial DNA is still unknown for the scientists or whether it influences their ability for implantation. There is however a possibility that the embryos with defects produce more mitochondria so they can survive but eventually they stop growing.
Wells said “These tests don’t make the embryos any better than they were in the beginning. There will still be patients out there, and many of them, who don’t produce any viable embryos at all. So it’s not going to guarantee future pregnancy rates to every patient overnight, but it will help,”
This procedure should in time be available in UK as the Human Fertilisation and Embryology Authority is considering the application for licensing. If the procedure is approved the test could be offered next year for extra 200 pounds to the price of PGS.
The chair of The British Fertility Society, Adam Balen said:
“There is a lot of interest in mitochondrial activity within eggs and developing embryos and this study presents a fascinating insight into the potential relationship between mitochondrial activity in genetically normal embryos and their potential for developing into a viable pregnancy,”
“It is still early days and the proposed test requires much more work and validation before application into clinical practice. There is no doubt this is a very important line of research and Dr Wells and his team are to be congratulated for what they have achieved to date.”