New, less invasive genetic test greatly improves pregnancy rates in older women with poor prognosis
Amsterdam, The Netherlands: A new test examining chromosomes in human eggs a few hours after fertilisation can identify those that are capable of forming a healthy baby, a researcher told the 25th annual conference of the European Society of Human Reproduction and Embryology today (Monday 29 June). Dr. Elpida Fragouli, from the Department of Obstetrics and Gynaecology, University of Oxford, UK, and Reprogenetics UK, said that her team’s work had already enabled seven ongoing pregnancies in a group of older women with a history of multiple failed IVF attempts.
"Out of 35 patients who had embryo transfers after the test, we achieved a pregnancy rate of 20%, which is exceptional considering the extremely poor prognosis of the women involved." she said. "This represents a doubling of the usual pregnancy rate for women who fall into this category, which is otherwise, at best, under 10% and, at worst, zero. To date, we have two live births from this group, and all the other women who became pregnant have maintained their pregnancies. The study is continuing, and we believe that we will achieve more pregnancies with the help of this technology in the future."
The scientists used the Comparative Genomic Hybridisation (CGH) technique to count the chromosomes in each egg. Unlike conventional screening strategies, using the fluorescent in situ hybridisation (FISH) method, which allows less than half of the chromosomes of an embryonic cell to be examined, CGH enables the evaluation of the entire chromosome complement. CGH was used to examine the fertilised eggs by looking at polar bodies, tiny cells that are a by-product of egg development. The chromosomes of polar bodies provide an indication of whether the corresponding egg is normal or abnormal; if the polar bodies have the wrong number of chromosomes, so does the egg.