12 eggs collected but only 5 mature: why?

[pjani]

I had eggs collected in an attempt to be a donor for my a family member.

I’m 37 but had conceived a DC naturally and had reasonable AMH (15) for my age so was hopeful.

But of the 12 eggs collected only 5 were mature, 2 fertilised and 1 made it to blastocyst. I’m disappointed.

Do others have experience of many ‘immature’ eggs? Advice on why it happens and what it might mean?

That does sound like a high drop off rate - it's the lack of mature eggs which looks odd which could be down to the specific stimming drugs you were on, how long you were on them and also when you were triggered? When you have a follow up I would ask for the sizes off the follicles on the last scan before you triggered?

The fertilisation to blast ratio is pretty normal - my clinic expects a drop off rate of 50% between fertilisation and blastocyst when you are in your mid thirties

What was the quality of your blastocyst like?

As a comparison I'm 36 with AMH of 12.9
Did mild stimulation IVF
14 collected
12 fertilised
3 made to day 3 and same number to day 5 blastocyst- average quality

My issue is poor egg quality hence my big drop off rate from fertilisation to day 3

I have found out that:

2 follicles were 16 (whatever the unit of measurement it, it doesn’t say£
2 were 15
2 were 14
2 were 13
2 were 12

This was at a scan on the Monday, I had the trigger Wednesday night for Friday collection.

Any thoughts, anyone, why I had 12 eggs but only 5 were mature?

I would say only the ones in the 15mm & 16mm follicles were mature.....maybe they triggered you too early?

In a natural ovulation situation the egg grows 1-2mm per day and is usually released when then follicle is 19mm - 21mm (usually 21mm)

If you triggered on Monday that would make

16mm = 20mm by collection
15mm = 19mm by collection
14mm = 18mm by collection

And that assumes they grow by the maximum amount

So you can see the smaller follicles you had were never going to have a mature egg in them