EMBRYO SCREENING BOOSTS 'OLDER' WOME's CHANCE OF MOTHERHOOD
Embargo: 13.00 hrs CET Monday 28 June 1999
EMBRYO SCREENING BOOSTS 'OLDER' WOME's
CHANCE OF MOTHERHOOD
Age no longer a handicap in fertility treatment say researchers. Older women undergoing IVF or ICSI* treatment can now have the same chance of achieving a successful pregnancy as younger women, thanks to a new technique which allows doctors to screen a single cell from an embryo before the embryo is transferred to the woma's uterus.
As women get older the risk of an embryo containing the wrong number of chromosomes in its cells - a condition called aneuploidy - increases up to 70-fold. Many aneuploid embryos don't implant and of those that do the result can be an early miscarriage or a severe malformation, such as Dow's syndrome. Aneuploidy plays an important role in the decline of fertility with age and is one of the major reasons behind lower IVF/ICSI success rates in women aged over 37.
But a study by a team of Italian researchers, using pre-implantation genetic screening (PGS) by a technique called FISH** to screen out aneuploid embryos, has achieved the same pregnancy success rate in women aged 38 to 44 as in their younger patients.
Dr Anna Ferraretti, Clinical Director of the SISMER Reproductive Unit in Bologna, told a news conference at the European Society of Human Reproduction and Embryology annual meeting today: (Monday 28 June) "Women planning IVF or ICSI in the final part of their reproductive life can now enter treatment feeling their age is not a handicap any more. PGS is able to overcome the natural reproductive failure that occurs due to their eggs aging."
Dr Ferraretti said that since September 1996, women over 37 entering SISME's clinic for several different infertility factors were asked to undergo PGS using the FISH technique to separate embryos carrying chromosomal abnormality from those evaluated as normal.
128 patients between 38 and 44 years who agreed to undergo PGS of all their IVF-generated embryos had the same pregnancy rate (41%) as 700 younger patients who underwent conventional IVF/ICSI treatment without PGS. The miscarriage rate in the older women was only 4%.
But 182 patients aged over 37 who declined PGS achieved only a 25% pregnancy rate and the miscarriage rate was 15%.
Because FISH technique is limited by using a single embryonic cell, there has been a 5-7% error rate up to now. Therefore the women were also strongly recommended to undergo conventional prenatal diagnosis to avoid the possibility of an affected baby.
Dr Ferraretti said: "The social, psychological and ethical implications of the poor chance of a successful pregnancy among older women has become evident as more and more women over 37 worldwide ask for help from assisted reproductive technologies. So to be able to offer these women the same chance of achieving healthy babies as younger women is an important and heartening step forward."
* IVF (in vitro fertilization): fertilization of an egg by sperm in a laboratory dish.
ICSI (intracytoplasmic sperm injection): process by which a egg is fertilized by injecting a
single sperm into the egg.
** FISH (fluorescence in situ hybridization): a molecular technique which combines microscopy with nucleic acid probes to localise specific DNA sequences on a chromosome. The researchers took a single cell from an eight-celled embryo without compromising further development and evaluated up to nine chromosomes (X, Y, 13, 14, 15, 16, 18, 21 and 22).
Abstract no: O-180
Margaret Willson (media information officer)
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