One of the reasons IVF outcomes are so unpredictable and uncertain is because it's a complex biological system, and there are lots of factors which determine success.
It's useful to think of these in terms of known factors ; and unknown factors .
For example, we know that the quality of the embryo ; and the endometrial thickness and texture will influence the chances of embryo implantation.
However, we also know that not every perfect embryo transferred into a perfect endometrium will implant, which clearly means there are lots of other factors which determine success, which we don't know enough about !
These include: genetic factors; epigenetic factors; and immunological factors , all of which still need to be studied and analysed.
At present, we include these under the rubric of "luck" and "fate" - which aren't very accurate or helpful terms !
This is why research and development is so important, and advances in reproductive science will ensure that the number of known factors will increase , while the unknown factors will progressively decrease.
However, it's still not possible for us to be able to measure or improve all the unknown factors, which is why we still can't predict which IVF cycle is going to be successful , and which one isn't.
We try to use all the technological tools available at our disposal, but our answers are not perfect and we need to live with this !
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