December 20: How can I improve my chances of falling .. Learn More

Why Do I Have Less Eggs Than Follicles and Even Fewer Embryos?

blastocyst culture

It is important to understand that not every follicle seen on ultrasound scan during an IVF cycle will have an egg collected from it.  It is expected that approximately 60-90% of follicles will yield an egg.  Occasionally there are may be fewer eggs collected at the egg collection  than might be expected and in some situations there can be no eggs.  Having no eggs collected is sometimes seen when there are a low number of follicles noted on the final scan before egg collection I.e. 4 or less.  Once the eggs have been collected, not every egg will fertilise. It is expected that approximately 70-80% of eggs will fertilise. However, once an egg has been fertilised, it does not necessarily mean it will be suitable for transfer or freezing.  For example from the eggs that do fertilise it is expected that approximately 1/3 of these will reach day 5/6 (called the Blastocyst stage). So if 9 eggs fertilized, it would be realistic to expect that 2-3 of these embryos would progress to day 5/6. Once the embryos have reached this stage it does not necessarily mean they will be suitable for transfer or freezing. It’s important to realise that these results are very individual.  If you have further question please don’t hesitate to speak with you specialist or  the scientific team.