London, June 26 (Reuters): Success rates of fertility treatments are set to rise thanks to a screening technique which allows doctors to select the healthiest embryos, a leading expert said today.
But the technique, known as pre-implantation genetic diagnosis (PGD), is also controversial because it has been used to select an embryo that is a genetic match to a sick sibling. Couples have been accused of creating babies to save an existing child. The two themes are likely to be centre stage when fertility experts meet in Madrid next week for a meeting of the European Society of Human Reproduction and Embryology (ESHRE).
“The question is whether we have the right, or should allow, this kind of technology to create babies to save others. I think this will be a big topic,” Professor Antonio Pellicer said.
Britain’s first genetically matched birth sparked an ethical debate earlier this month after a boy was born who could help to cure his older brother who suffers from a rare form of anaemia.
But Pellicer, the co-ordinator of the Madrid meeting, said PGD could be a real help to couples with fertility problems.
“One of the major advances in fertility treatment is that today we are able to analyse, to screen, the embryos better than before and PGD has actually become a tool to search for normal embryos,” he said.
The technique is expected to improve the success rate of fertility treatments, which is currently about 27 per cent, because a healthy embryo is more likely to implant in the woman’s womb and result in a live birth. “Abnormal embryos usually do not implant and if they do implant, at some point the woman miscarries,” said Pellicer, a professor at the University of Valencia.
Being able to select the healthiest embryo can also reduce multiple births, which can be dangerous for both the mother and child, because fewer embryos will need to be transferred into the woman to achieve a pregnancy.
The implantation rate of a single embryo in the womb has increased from about 6 per cent in the early 1980s to nearly 40 per cent today, according to Pellicer. “Looking at chromosomes has become a tool to help clinicians to check for the best embryos to be replaced (in the womb),” he said. Scientists usually screen embryos for seven or eight of the 23 chromosomes in humans, which gives them a good picture of how normal the embryo is.
As well as helping doctors pick out the best embryos, PGD also can detect single gene diseases such as cystic fibrosis.
“We are in a stage in which we will be able to diagnose most of the problems the embryos have. However, to manipulate the contents of a human embryo seems to be very improbable for the moment,” he said.