The Ramblings of a Middle Aged Fertility Physician whose life revolves around Eggs, Sperms & Embryos....
Thursday, February 19, 2009
World's first pregnancy using IVF egg-screening technique
A British woman has become the first in the world to conceive using a new IVF technique that could more than double the success rate of pregnancies. The 41-year-old woman was treated after suffering two miscarriages and having 13 courses of IVF, none of which led to a baby.
The technique allows doctors to screen fresh eggs for abnormal chromosomes, which are a major cause of miscarriage. Many embryos that have damaged or missing chromosomes miscarry, but others go on to produce conditions such as Down's syndrome.
The woman, who was treated by doctors at the Care Fertility Group in Nottingham, is expected to give birth in the next two months. Fertility clinics have long sought a way to check eggs or embryos for major chromosome abnormalities. A healthy egg carries 46 chromosomes – 23 pairs – but before it can be fertilised it needs to ditch 23 of these, which it packages into a structure called a polar body. The new technique checks the chromosomes in the polar body.
Doctors at the clinic collected nine eggs from the woman after stimulating her ovaries with standard hormone-based drugs. Using the new screening technique, they found that only two had intact chromosomes and so were likely to implant and lead to a successful pregnancy. Both embryos were implanted into the woman and one went on to a pregnancy.
Simon Fishel, director of the Care Fertility Group, said the milestone demonstrated the "wonderful ingenuity of humankind". The screening process costs £1,950 on top of standard IVF treatment, which can £3,500.
"One of the main reasons why IVF doesn't work is chromosomal abnormality," said Fishel. "Full chromosome analysis offers huge hope to many couples who have a poor chance of conceiving, those who have had many failures, and for those who want to maximise their chance at each attempt. We now have the best tool for achieving this."
Up to half the eggs of younger women, and up to 75% in women over 39, have abnormal chromosomes.
The technique, called polar body array comparative genomic hybridisation, is the first that can check all of an egg's chromosomes to see if any are missing or duplicated.
The process uses a laser to make a small incision in the outer membrane of the egg, from which doctors can extract the polar body containing the 23 chromosomes that were expelled before fertilisation. The doctors then use a computer-driven screening process to check if all of the chromosomes are present.
"This screening method has the potential to improve birth rates, minimise the incidence of miscarriage and birth defects caused by chromosomal irregularity," Fishel said.
Fishel's clinic has agreement from the government's fertility watchdog, the Human Fertilisation and Embryology Authority, to offer the technology to any of their patients. Because the procedure is experimental, however, it will not yet be offered on the NHS.
The HFEA has ordered UK fertility clinics to take steps to reduce the number of twins and triplets born to IVF couples. In most cases, this will involve transferring only one embryo to the womb at a time. Doctors believe the new technique will allow them to select the most promising embryos, increasing the chances of a succesful pregnancy.
A previous trial conducted last year by the Care Fertility Group and an American team suggests the technology could double the number of embryos that implant in the womb, from 25% to 50%.
Fertility doctors at other clinics cautiously welcomed the development today. Stuart Lavery, a senior consultant gynaecologist at Hammersmith Hospital in London, said: "Although it is still at a very early stage, this technique may offer a new diagnostic and therapeutic hope to couples who suffer from repeated implantation failure in IVF."
"Previous methods of screening embryos to detect abnormality have not proven to be sufficiently effective in increasing live birth rates. We need further research in this area so questions of reliability, efficacy and safety can be fully answered."
Tony Rutherford, chair of the British Fertility Society, said: "It is absolutely essential that these new techniques are subject to further rigorous research, and should only be offered to patients within the context of a robustly designed clinical trial, carried out in suitably experienced centres."
Around 6,000 babies a year are born in the UK to otherwise infertile couples as a result of IVF. The technique was developed in the 1970s and the first test tube baby, Louise Brown, was born in 1978.
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