Why are FET success rates lower?

[Avocadosmoothie]

Hi! My clinic has a 40% success rate with fresh embryos but only 22% with frozen. That's based on 2015 data. Does anyone know why the rates are lower? Thanks!

That's odd and not the norm. Maybe how they freeze them so they aren't defrosting successfully?
Or do they do unmedicated cycles for fet?
Overall, at more successful clinics, assuming embryo survives defrosting, the pregnancy rates are similar for fresh and frozen (in fact some places are getting better results from frozen embryos)

Our clinic are 52% for fresh (unlucky me!) and 48% for fet I think. Double check your clinic stats, that seems very odd, the figures should be very similar x

Slightly off but still >15% difference 🤔

Do you think the FET results include embryos that don't survive the thaw? I presumed the results just show rate of embryos that are actually transferred

The fet is live birth, do they not have a direct comparison for fresh live birth? That will (very sadly) bring down the fresh percent you've shown there, so the fet and frozen are more aligned perhaps?

Ah I hadn't noticed that. The live birth fresh embryo much be lower than 40% then. My clinics results sound quite bad compared to others!

So only 15 of the embryos failed to defrost on those stats (cycles started vs embryo transferred).
25% live birth rate when they do transfer (assuming one embryo transferred at a time) for frozen vs 30% live birth with a fresh cycle.
They are reasonable stats and compare ok with national stats.
Pregnancy rate doesn't matter. Taking a baby home is the point.

25% is so disheartening! Do you know how much your chances increase of you transfer two embryos? I've heard it's very small so probably isn't worth the risks that could come with twins...?

25-30% is actually pretty good (if you compare it to sex - the rate for getting pregnant is about 10% per cycle...)

www.thefreelibrary.com/One-blastocyst+transfer+as+successful+as+two%3a+results+of+two+U.S....-a0128876049

Some people say rate of pregnancy increases by 10% with 2 embryos but the rate of twins increases by 50% which decreases the live birth rate significantly.

Generally fet have a slightly higher rate of success

Some clinics now freeze all eggs and transfer following konth

1. to give body a break to recover from drugs and ec
2. if they defrost well likely to implant

DD is a fet. Our 5th go and 2nd fet and is now 3.5mths

I was told that the difference between frozen and fresh was tiny by the consultant.

Thanks everyone. It is odd that at my clinic FET rates are 15% lower than fresh, I will definitely ask why next time I speak to our consultant!