A new method of embryonic screening could double women’s chances of selecting an embryo with the best chances of developing into a baby.

Comparative genomic hybridisation (CGH) is a marked improvement over previous screening methods, writes Tony Rutherford, chairman of the British Fertility Society, in the London Times because it can weed out more potentially unsuccessful embryos. CGH uses cutting-edge vitrification techniques to freeze embryos at least 5 days old (known as blastocysts). They then extract a number of cells in order to find the exact number of chromosomes.

This new embryonic screening method allows potential parents to locate defect-free embryos with the highest statistical chance of developing into defect-free babies.

CGH improves on pre-implantation genetic screening, in which a single cell is taken from an embryo in its early stages. Rutherford says that this is not very reliable or efficient. CGH tests all 23 pairs of the blastocyst’s chromosomes, allowing for more than doubled accuracy in finding genetic defects.

The scientist who has developed the technique, Dr Dagan Wells, of Oxford University, said that the results were "astonishing". The technique would be most useful for women around 40 whose embryos frequently are chromosomally defective. "You can imagine the pressure felt by an IVF patients who’s struggled for years to achieve a pregnancy and then discovers they are pregnant but the baby has something like Downs," he told the Adelaide Advertiser.

There are no guarantees for this expensive treatment, however; embryos may not reach blastocyst stage, and other factors may still lead to a failed pregnancy, such as a failure of the embryo to implant properly in the uterus. ~ London Times, Oct 19; London Times, Oct 18; Adelaide Advertiser, Oct 20