It used to be that everyone would say ‘fresh is best’ when it comes to IVF success rates. This common idiom referred to the fact that women were more likely to get pregnant when a fresh embryo, between day 3 and 5 of development, was transferred to their uterus rather than an embryo that had been frozen.
We look at how this isn’t the case anymore and you should consider using your frozen embryos rather than embarking on a fresh cycle.
What is a Frozen Cycle?
For the avoidance of doubt a frozen cycle means the thawing of an embryo and transferring it into the patient (a fresh cycle is when eggs are collected, fertilised and typically one ‘fresh’ embryo is transferred into the patient). Fresh cycles are far more burdensome for patients requiring higher levels of stimulation, an egg collection and take longer than a frozen cycle would do. Anyone considering a frozen cycle must have had an egg collection at some point to generate embryos to freeze.
Fresh success rates are much than frozen, aren’t they?
Since the beginning of IVF treatment in the UK fresh cycle success rates have always been significantly better than frozen cycle success rates. For many patients the gap between fresh and frozen success rates meant they would rather undergo multiple fresh cycles than entertain the prospect of a frozen cycle. Frozen cycle success rates have improved dramatically in the past 5 years and that’s primarily down to, amongst other reasons, the adoption of improved freezing techniques within IVF clinics.
What’s the advantage of a frozen cycle?
One of the major differences between fresh and frozen cycles is cost. A fresh cycle is typically at least 3 times higher in cost than a frozen cycle.
- Patient Burden
As I mentioned above the physical burden of a fresh cycle is significantly greater than a frozen cycle. The impact of this burden should not be underestimated.
- Endometrial Receptivity
Within a fresh cycle the clinic is trying to ensure that you are adequately stimulated to collect a decent number of eggs safely. The clinic is also trying to ensure that the lining of your womb (endometrium) is not adversely affected by the medication used to stimulate you. The endometrium is crucial as this is where your embryo will implant. For some patients it may be easier to manage their endometrium during a frozen cycle and consequently provide a better outcome (increased chance of pregnancy).
What is the freeze-all approach?
A freeze-all is where all the embryos generated after an egg-collection are purposefully frozen and no embryo is transferred. This may be for a number of reasons but primarily it is done to give the clinic a better chance of ensuring the endometrium is in optimum condition before transfer.
A typical example would be a patient with elevated progesterone (a key hormone in the development of the endometrium) levels after egg-collection. In this type of patient, the clinic knows that the chances of implantation are reduced and so a freeze-all may the preferred approach. This gives the clinic an opportunity to work with the patient to give the endometrium its best during a frozen cycle.
It’s worth highlighting that the freeze-all approach may not be in every patient’s best interest. The clinic will be reluctant to freeze low graded embryos or to risk freezing embryos for patients who have produced a low number (there’s no guarantee that any given embryo will surviving the freezing and thawing process).
Frozen success rates continue to improve, which is welcome progress. This is greatly encouraging for patients who have embryos to freeze and for those for whom a freeze-all is in their best interest. There are clear advantages to a frozen cycle in the reduced cost / burden and potentially better management of the endometrium. However, for the majority of UK patients the fresh cycle approach will be taken by their clinic.