CGH screening doubles the chance of pregnancy in IVF
Researchers at Oxford University have developed a genetic-screening test, termed as comparative genomic hybridization (CGH), that could more than double the chances of pregnancy for women undergoing IVF fertility treatment.
"We thought we'd get an advantage using this procedure, but we didn't think it would be anything like what we've seen," said Dagan Wells, developer of the CGH and a fertility specialist at Oxford University and the genetics screening company Reprogenetics UK.
Initial trials have revealed that 66 percent women undergoing IVF fertility treatment conceived if their embryos were checked for abnormalities before being implanted in the womb.
On the other hand, less than 30 percent of the women became pregnant when CGH, which essentially checks chromosomes in the developing embryo, was not used.
Wells described the improvement in pregnancy rates amongst the 42 women, screened with CGH and then treated, as “astonishing”.
The average age of these women was 39 and they had at least two failed IVF cycles behind them. Many of them were on their “last chance” at conceiving with fertility treatment.
36 women (86 percent) of the 42 participants conceived after undergoing the CGH.
“We were taken aback by the impact it had on the success rates,” Dr Wells said. “I think it’s at the point now that we can say with great confidence that we are seeing a positive effect of this.”
Quality of embryo does not improve
Wells claimed that only the embryos with the greatest likelihood of becoming a fit baby were used in the fertility treatment. The CGH enables doctors to take a biopsy from a five-day-old IVF embryo which is made up of more than 100 cells.
The biopsy is scrutinized under a microscope for signs of aberrations in its chromosomes, the strands of genetic material that carry DNA. The procedure, thus, distinguishes the embryos that can lead to a healthy baby from the embryos that do not have such characteristics.
The procedure, however, does not improve the quality of a woman's embryos.
“It's important to say that it doesn't make the embryos any better than they were. This is simply a way of identifying which embryos you should use if you have a number to choose from. It's way of making sure you don't waste the patient's time by transferring embryos that won't make a baby," said Wells.
The test, approved by the fertility watchdog, the Human Fertilization and Embryology Authority, is available for £2,000 at select private clinics in Britain.
The findings are scheduled to be presented this week at the American Society for Reproductive Medicine’s annual conference in Atlanta.