I expect for most of you the answer is no. But we should have. And certainly for any woman over the age of 40 with unexplained infertility, recurrent miscarriage or having had several failed IVF attempts, you absolutely should have heard of it.
In this article we discuss the affects of chromosomal abnormalities on pregnancy outcomes and whether preimplantation genetic screening or karyotyping is worth it. Spoiler alert: The short answer is, yes!
So what’s a balanced translocation and where does it come from?
It’s a genetic condition whereby parts of a chromosome have broken off and attached to other chromosomes in another location. In other words, sections of two chromosomes have switched places. It can be entirely harmless or entirely serious depending on which chromosomes have attached where.
You might have a chromosomal abnormality affecting the egg or the sperm and it is thought that “50 -75% of spontaneous miscarriages result from numerical chromosomal abnormalities in the embryo or foetus.” (Fritz & Speroff)
Does age matter?
Yes. “Data derived from numerous studies reveal that older women and women with a history of recurrent pregnancy loss produce more aneuploid embryos than younger women”. (Fritz & Speroff)
Is it common?
Balanced translocations are relatively common, a 2-7% finding among infertile couples. It can affect the man or woman or both - making it a condition we really ought to know more about. (Ching, 2012)
How can we find out if we have it?
Preimplantation genetic screening (PGS) is a relatively new diagnostic and one in which most UK fertility clinics know little about, let alone offer it as a service.
It is used as an adjunct to IVF whereby the blastocysts are screened for chromosomal abnormalities before being transferred. Generally speaking, half of the blastocysts will be discarded leaving behind the sound ones for implantation.
If you are unable to garner any blastocysts for PGS you can have karyotyping which involves taking blood samples from both parents which are then examined for chromosome arrangement.
So why aren’t we told?
When it comes to fertility, most clinics still like to use the classic ‘get out of jail free’ card - The more attempts at IVF you have, the bigger the chance that one will stick. And it’s true. Even with balanced translocation there’s a chance that one or more blastocysts will still be viable for pregnancy. But the ‘get out of jail free’ card doesn’t take into account the financial and more importantly, emotional toll that multiple failed IVF attempts and/or pregnancy losses have on a person.
But in order to give a more well-rounded argument the official line is this: “IVF with pre-implantation genetic diagnosis for reasons of advanced maternal age or in couples with unexplained recurrent pregnancy loss can increase implantation rates and decrease miscarriage risk, but have not increased live birth rates. Consequently, the associated costs in couples without other specific indications for IVF cannot be justified.” (Fritz & Speroff)
Cost aside, wouldn’t knowing that there is a reason for your infertility justify the diagnostic? This is why I strive to explain “unexplained infertility”. It can all be explained with the right diagnostic. And with an explanation, patients are more informed to make decisions over their own fertile future. If the odds are stacked against them and all diagnostics are not pointing in their favour then it might be time to opt for an egg or sperm donor. However for most, the option of donated eggs is presented at a time when they’re at a loss to know what to do next. It then becomes an agonising decision to give up on their own biological children in the quest for a child altogether. It is my belief that, presented with all the facts, a couple can make an informed decision and probably bypass a lot of the emotional anguish.
So if you’re interested in any of the above, don’t talk to your fertility consultant. As with all my advice - whether it be sperm DNA fragmentation, a varicocele, an underactive thyroid, a balanced translocation. Their answer will invariably be to throw another IVF at it. So instead let’s get informed. Do your own research and don’t just rely on the ‘experts’.
Extracts taken from: Clinical Gynaecologic Endocrinology and Infertility (Eighth Edition) by Marc A. Fritz and Leon Speroff
Ching, 2012, Presentation and Treatment of Subfertile Men, National Institutes of Health,
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Verity Allen - BSc, BA, MBAcC, Lic Ac