Sunday, November 27, 2016

Why do most IVF cycles fail ?

The commonest reason for IVF failure is implantation failure. Even when we transfer good quality embryos inside the uterus , we know that most IVF cycles will fail. This is very frustrating for patients,  because they expect that their embryo is going to become a baby - which is why many patients fondly think of their embryos  as being embies !,  When a good quality embryo doesn't implant, they blame themselves . They also demand an explanation from their doctor  - especially when he was very optimistic and hopeful at the time of the transfer ( as so many IVF doctors are, in order to build up their patient's hopes).

The doctors then orders a series of tests , primarily to pacify the patient, even though he knows that the tests are pointless and don't provide any useful clinically actionable information .  This is because the uterus is a biological black box , and in vivo implantation isn't a process we can study or control after transferring the embryos inside the uterus.

However, when 2-3 cycles fail, patients start getting desperate, and start clutching at options such as surrogacy, because they feel this will help them to bypass the problems which the doctor cannot identify.

However, we need to remember that the failure of embryos to implant is the biological norm. The truth is that most fertile women (even those who have sex every single day) will not get pregnant every month they have sex, and the reason for this is that their embryo does not implant. After all, if the woman is young; ovulates regularly; has open fallopian tubes; and her husband has a good sperm count, and they're having sex everyday , this means that the sperm must be reaching the egg , and this must be fertilizing. If the woman still doesn't get pregnant each month she has frequent unprotected sex, this clearly shows that embryo implantation fails in most cycles, even in fertile young women.
Let's not forget that fecundity rates are about 20% per cycle for young women.

It typically take fertile women five to six of regular sex months before they get pregnant, which is why the definition of infertility is not getting pregnant even after trying for a year. This is why we say that human reproduction is not efficient.

There's no reason for us to expect IVF to improve this efficiency  ! What IVF does is allow us to compress time, but the chances of the embryo having a genetic defect remain the same. This is the reason why most embryos don't implant every cycle.

The problem is that when you are having sex in your bedroom, you don't mind the failure of implantation all that much - you can just look forward to trying again the next month !  However, when your precious embryos fail to implant after IVF, it's much harder to deal with this failure.


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