Genetic testing of embryos could increase IVF success rates for women over 40.

Genetic testing of embryos increases the chances of a successful pregnancy in women undertaking in vitro fertilisation (IVF). More than that, however, genetic testing makes IVF “blind” to a woman’s age.

Without testing, women over 40 have an 8.5 per cent chance per embryo of falling pregnant with IVF. With testing the “age factor” is reportedly eliminated. For women under 30 the success rate is 40.1 per cent.  

First off, what is genetic testing?

Genetic screening of embryos in IVF involves an “embryo biopsy” where a selection of cells are tested for anomalies in the number and structure of chromosomes. Genetic screening of embryos in IVF is commonly referred to as pre-implantation diagnosis (PGD).

Normally, every human and embryonic cell contains 46 chromosomes – half from each parent – arranged in 23 pairs. If an error occurs during fertilisation, and the cells are left with an extra or missing chromosome, this will result in an anomaly in the fetus and, if the pregnancy comes to term, the child. The most common result of this is Down Syndrome.

How does it help women over 40?

The integrity of a woman’s eggs declines with age, along with her overall fertility. That’s why the chances of women falling pregnant after 40 is significantly reduced and, if a women over 40 does fall pregnant, the risk of a chromosomal anomaly is high.

This could be changed with genetic screening.

“The greatest advantage in “genetic testing” is that you are transferring an embryo that is known to have the normal number of chromosomes. This eliminates age as a factor in IVF,” Fertility specialist at the City Fertility Centre Adelaide, Dr Stephen Lane, said. “If the embryo is ‘normal’ the pregnancy rate is almost the same across all age groups.”

Who else does it help?

Other than women over 40 trying to fall pregnant, there are a number of cases where genetic testing might be beneficial to women undergoing IVF. For example:

• A woman in her 20s with recurrent miscarriages.
• A woman who is over 35, or in her 40s, wanting to minimise her chances of having a baby with down syndrome.
• Couples with a family history of chromosomal disorders.
• Couples who have had multiple “failed” IVF attempts.
• Couples with sperm abnormalities, uterine abnormalities, endometriosis, lifestyle issues.

“It is also reasonable to have pre-implantation testing in your first IVF cycle no matter how old you are,” Dr Lane said. “It can be quite surprising to find how many embryos that look ‘high quality’ when tested are not genetically ‘normal’. Even in your late 20s the percentage of abnormal embryos that appear to be ‘high quality’ can be around 50 per cent.”

“Given the stress of a failed cycle, and the self doubt that follows. Or a miscarriage at eight or 12 weeks followed by a few months recovery, followed by another cycle that may cost between $2-5000. Taking the time to do genetic testing may be a reasonable option for any couple considering IVF, no matter the reason or the age of the couple,” Dr Lane said.

According to Dr Lane, there are two different types of genetic screening.

1. The most basic test is to check the number of chromosomes. This is relatively cheap and available at most IVF clinics in Australia. This identifies problems such as Down Syndrome (an extra Chromosome 21), Turner Syndrome (one instead of two X chromosomes), Klinefelters Syndrome (a man having 2x (female) chromosomes instead of one). This may save a traumatic decision to terminate a wanted pregnancy in the second trimester when the abnormality is discovered.
2. Testing for specific gene abnormalities that may be inherited such as Cystic Fibrosis, Muscular Dystrophy, Haemophilia, Thallassemia and “Translocations”. These tests require special gene “probes” to hunt out the abnormal gene within a chromosome, and require much more intensive testing. Not all clinics provide this service and the embryos may need to be “sent” to another clinic to do the specific testing.

Are there any risks involved?

Dr Lane says there are limited risks associated with an embryo biopsy. That it’s well-established and widely-performed procedure.

“Embryo biopsy has been performed for many years, and no specific risk has been associated with embryo biopsy,” Dr Lane said. “The sample is not taken from the actual baby but from the part of the embryo that becomes the placenta which is reassuring to couples.”

“Unfortunately, in around 10% of attempts at biopsy either not enough cells are removed and the test does not work, or the cells do not “amplify/divide” enough to get a definitive result,” Dr Lane continued. “The embryo is still frozen and available for transfer at a later date, but the genetic status of the embryo is unknown.”

Genetic testing is offered at many IVF clinics. While the cost of testing varies, the cost of a basic test usually falls between $400 and $500 per embryo tested, while testing for specific abnormalities might cost within the $3,000 to $5,000 range. There is no Medicare rebate offered.

“Given a failed cycle will also cost, and involve significant time and stress, some couples may feel that the upfront cost of genetic testing is worth the money,” Dr Lane said.