Almost 90 per cent pregnancy rate following full chromosome count on IVF embryos

A genetic screening technique with the potential to dramatically improve the chance of an IVF cycle resulting in a healthy baby is being pioneered by Genea, with fantastic results for patients.

The technique – microarray comparative genomic hybridisation (CGH) – was first used in Australia by scientists at Genea and allows a full chromosome count of embryos created using IVF.

Random chromosome abnormalities are one of the main causes of failed IVF cycles and of repeated miscarriages in both fertility patients and women who conceive naturally.

But by using CGH scientists can ensure that only embryos that contain the correct number and sequence of chromosomes are considered for transfer – with dramatic results. Where there is a chromosomally normal embryo to transfer after CGH screening, almost nine out of 10 patients achieve a pregnancy.

New data, to be presented at an international fertility conference in Melbourne today, reveals a pregnancy rate of 88 per cent – based on patients aged less than 38, where a fetal heartbeat was detected at seven weeks gestation. For women aged more than 38, the pregnancy rate is 65 per cent.

Genea Scientific Director Steven McArthur said the pregnancy rates surpassed all expectations.

"It is an exciting development for patients, many of whom have experienced failed IVF cycles or miscarriages, to be able to access a service that provides such a high chance of achieving a healthy pregnancy,” Mr McArthur said.

“Microarray CGH offers us the equivalent of prenatal screening, but at day five of the development of an embryo. The main benefit for a couple is time, which can be crucial especially for women in their late thirties. Being able to identify which embryos are free of chromosome abnormalities has the potential to minimise the number of treatment cycles, reducing both the emotional and financial stress for patients.”

During IVF, embryos are created by combining eggs and sperm in the lab. At Genea, they are closely monitored for five days and those that are developing normally will be considered for analysis and transfer.

But even if an IVF embryo appears to have developed normally when examined under a microscope, there can often be hidden errors in its genetic makeup that mean it will never result in a healthy baby. With CGH, a detailed analysis of all 46 chromosomes can be carried out before a pregnancy has even begun.

Genea Medical Director Associate Professor Mark Bowman said CGH would not be recommended for all IVF patients and was most appropriate in instances where maternal age was likely to increase the risk of chromosome abnormalities or where women had unexplained recurrent miscarriage.

“Repeated IVF failure and recurrent miscarriage are common problems as women get older, as a result of older eggs,” Assoc. Prof Bowman said.

“If we can attain a good number of eggs in an IVF cycle, then CGH offers those couples the chance to achieve a healthy pregnancy faster than they would have by undertaking IVF without testing.”

Australia’s first CGH baby was born in November 2010 to a Genea patient with a history of recurrent miscarriage. To date another 14 women have had healthy babies after the use of the screening and there are 13 on-going pregnancies.

The Genea CGH success data will be presented at the 14th World Congress on Human Reproduction – an international fertility conference taking place in Melbourne from 30 November – 3 December 2011.

About microarray CGH:

  • A small number of cells are removed from the growing embryo five days after fertilisation. They are taken from the trophectoderm, the part of the embryo that will form the placenta and the inner cell mass that will become the baby is not touched. Embryos are frozen while the CGH analysis is carried out.
  • The DNA is analysed and displayed on a computer screen as 60,000 tiny dots – each corresponding to part of the human genome. Lasers scan the fluorescent dots and compare the DNA to that of known normal DNA. A detailed image of each chromosome is created, allowing scientists to report on specific parts of chromosomes where genetic material is missing or has been added.

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Meline Walton
Media & Communications Manager
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