Firstly, your clinic isn't interested in transferring embryos that don't at least have a reasonable chance at creating a pregnancy.
Most countries now have 'league tables' where you can easily find the 'success rates' for individual clinics. People use these tables (mistakenly in my opinion) to help them choose which clinic to go to, which clinic to use when creating their families.
So the clinics need to make sure that their 'success rates' are at least on par with other clinics in their area. They need to make sure that every embryo they transfer has at least a reasonable chance of creating a pregnancy.
Studies tell us various aspects of an embryo can influence whether it is likely to create a pregnancy or not. Over many many years of assessing millions of embryos and comparing data around the world, we have gathered enough information to tell us that embryos that have certain features probably carry a greater chance (statistically speaking) of resulting in a pregnancy and a live birth. Using this information, and information gathered from their OWN experience, in their own culturing conditions, clinics then set a benchmark for embryo quality - below which they will not transfer or freeze an embryo
That doesn't mean that embryos 'below' that grade cannot give rise to a pregnancy... just that statistically speaking, the chances are lower. It also doesn't mean that anything ABOVE that grade WILL create a pregnancy... just that the chances might be higher.
But whether an embryo has a 20% chance of giving rise to a pregnancy, or a 25% chance (or maybe even a 50% chance!) doesn't really mean anything to you when you're counting the days to your pregnancy test. I mean, are you going to be 20% excited when it works? or 20% disappointed when it doesn't? after all - you knew there was an 80% chance that it wouldn't work .... it sounds a bit crazy when you say it like that doesn't it?
I have seen so many pregnancies from the lowest grade embryos, after all of the 'high grade' ones have been used and failed. I have seen pregnancies from low grade embryos that were destined to be discarded, where the patient insisted on having a transfer for closure (after multiple failed cycles).
and I have seen beautiful, high grade embryos fail time after time...
The grade of your embryo is really useful for the lab, its useful for general statistics, its useful for decision making inside the confines of the lab.
Its potentially useful for family planning - if you need to bank embryos to complete your family
But mostly - it's not useful at all. Not for you.
If the clinic think your embryo is good enough to transfer or to store for later use - it's definitely good enough to make a baby.
So then lets look at Implantation failure….. such a tricky one!
When we start to talk about implantation failure, it's important to really know what that is and what it means.
According to a study I read the other day, the term “implantation failure” refers to two different types of cases, those in whom there has never been evidence of implantation (no detectable hCG production) and those who have evidence of implantation (detectable hCG production) but it did not proceed to beyond the formation of a gestational sac visible on ultrasonography (1).
Implantation failure is kind of a mis-nomer though as it has been reported that spontaneous pregnancy is achieved in only about 25-40% of healthy fertile women during the first cycle of intended pregnancy. That means that only up to 4 women in a group of 10 healthy fertile women will conceive in the first month of trying. So it’s much more common that implantation will NOT happen (6/10 women will not conceive) and using the word ‘failure’ has such negative connotations.
When conception doesn’t happen when you’re trying naturally, it’s hard to know where the ‘problem’ actually is. But when you’re having IVF, it's much easier to come up with a term like ‘implantation failure’... we know a 'healthy' (we think) embryo was put into the uterus at roughly the right time... so then when pregnancy doesn’t happen, it’s easy to start the blame game on ourselves… ‘there was a nice embryo there and now there’s nothing - it must be me’
But this is not really true… There are a number of factors that impact implantation, it’s not all down to the ‘grade’ of the embryo.
the embryo itself has to be chromosomally normal. The ‘grade’ doesn’t always correlate to the chromosomal status),
the embryo needs to have the energy reserves to power all the of DNA replications and divisions, and the cellular divisions needed to continue growing
the uterus (the uterine environment and the thickness of the uterine lining will both have an impact),
the timing of the ‘landing’ of the embryo - it has to land in the right place at the right time - kind of like the lunar module! (in IVF this can be related to timing of the embryo transfer),
and the progesterone levels in the luteal phase (the bit after ovulation, or after embryo transfer).
Each of these aspects could be the topic of an entire blog on their own. Some can be affected by diet and lifestyle - some can't.
And lets face it - lots of people conceive without ever knowing anything about any of this! Infuriating isn't it!!
There are of course lots of things to consider with each of these and if you would like to chat about your own specific situation and what could be contributing (and what you can, or can’t, do about it) - reach out and let’s chat.