My clinic states that somewhere between 50-75% of eggs should fertilise.

My first cycle, we had 26 eggs, but only 21 were mature, with ICSI, 15 fertilised.

My second cycle, 32 eggs, 30 mature, 20 fertilised. I don't recall the reasons with the first cycle, but with the second one, they told me that the eggs that weren't fertilised weren't good enough - they described them as "grainy".

5 from 12 isn't necessarily bad - it could be that some of the eggs that were collected weren't mature enough, or weren't good quality like those that weren't used for me.

I would suggest that it's certainly worth asking your clinic about the reasons for the lower fertilisation rate, and perhaps find out if they think that ICSI might overcome this in the future. Although, it's not a foregone conclusion that you will need to do this again - you have an embryo trasnsferred, you have some that will hopefully go into storage - it could very well be all that you need. Good luck!

BW