New procedure to spot viable IVF embryos
Reported May 14, 2008
Fertility researchers have developed a new procedure to be used in IVF treatment that could “revolutionise” success rates within two years.
When couples attend fertility clinics for IVF, eggs from the woman are fertilised with sperm and the resulting embryos allowed to develop in the laboratory for five or so days. After his medics then select what look like the best to be implanted into the womans womb.
But there is no reliable way of the best quality embryos most likely to create a successful pregnancy, and clinic staff tend to decide which embryos to implant on the basis of some “fairly crude tests”, says an Australian team.
The team is honing a DNA fingerprinting test to select the best embryos so only one needs to be transferred into the mother.
“This would effectively reduce multiple pregnancies, which is a priority in the field of assisted reproductive medicine at present.”
Around one per cent of all births in the UK are the result of IVF treatment and the latest figures show 32,600 women underwent treatment resulting in 11,000 births.
Each cycle costs on average £4,000. Dr David Cram, of Monash University, Australia, and colleagues report in the journal Human Reproduction has used DNA fingerprinting for the first time to identify which embryos have implanted after IVF and developed successfully to result in the births of healthy babies.
The technique, combined with sampling of around 20 cells from the very early embryo, before implantation in the womb, opens the way to pin-pointing a handful of genes that could be used to identify those embryos most likely to result in a successful pregnancy.
Dr Gayle Jones, a co-author at Monash, says the team hopes to have a hit list of genes for testing for viable embryos within two years: “We believe that it will be possible to refine our gene set to a smaller number of genes that is more highly predictive of a blastocysts (the technical name for the embryo at this stage of development) viability and ability to develop to a term pregnancy when transferred to a receptive uterus than current selection criteria.”
Pregnancy rates vary around the world and are somewhat dependent on the make-up of the patient population and the clinic practices – for example, older patients have a much poorer outcome than young patients.
In Australia/New Zealand in 2005 the pregnancy rate per transfer was 30 per cent, similar to that in Europe, she says.
A spokesman for the Human Fertilisation and Embryology Authority, HFEA says it is monitoring these kinds of technique and adds: Multiple pregnancy following IVF treatment is the single greatest health risk for women and the children they carry.
“The HFEA is currently working with professional bodies and patient groups to reduce the number of multiple pregnancies. The professional bodies are developing professional guidelines for embryo selection. Better embryo selection will be helpful to the profession in terms of tackling this risk for women undergoing IVF.”
One in four IVF pregnancies is multiple, compared with one in 80 for a natural conception.
At present, multiple embryo implants are still allowed but are restricted to two embryos in most cases (three are allowed if there is good cause if the mother is older or there have been a number of failed previous cycles).