Call BCRM on 0117 259 1159 or click here to email us

What is FET?

A Frozen Embryo Transfer (FET) is where embryos, which were frozen following IVF or ICSI treatment, are thawed and transferred (implanted) into the womb.

Learn more by clicking this link

At BCRM we use the most advanced technique known as “vitrification” however, not every embryo created is suitable for freezing, our Embryologists work out which embryos meet the criteria and inform you of the possibility to freeze embryos.

The embryos are usually frozen and stored at the blastocyst stage 5-6 days after egg collection.

There are two types of FET treatment.


Natural Cycle FET:
This is used in women who have regular cycles and ovulation, no drugs are used. Embryos are transferred after a positive ovulation test.


Programmed Medicated Cycle FET:
In a programmed FET you take medication, usually Estradiol tablets or patches to grow the lining of the womb until such a stage they are ready to receive embryos for implantation. Usually for 2 weeks and this is followed by progesterone pessaries to support implantation and development of the baby until 12 weeks of pregnancy.

Frequently asked questions

If we freeze top quality blastocysts, we find over 95% survive the thaw process ready for transfer.

In our hands the the success rates of FET treatment are similar to fresh IVF or ICSI treatment. In some cases the success rates are higher because the lining of the womb is not over-stimulated by high estrogen levels. The success rate also depends on the age of the woman when the embryos were frozen and not when transferred. It is for this reason we sometimes recommend a deferred IVF treatment cycle.

Embryos can be store indefinitely with no deterioration over time. However, we do not routinely store embryos beyond 10 years.

Less medication: no injections are required

No risk of OHSS: this is because the ovaries are not stimulated

Less stress: FET treatment is has a high chance of success because we only freeze top quality blastocysts and there is no ovarian stimulation, egg collection and therefore less visits to the clinic as well as less discomfort. This is particularly so in natural cycles where we have excellent success rates.

Less expensive: the cost of FET treatment is less than a third of a fresh treatment cycle of IVF or ICSI

Frozen Treatment Cycle Success Rates

Data obtained from HFEA website IVF/ICSI, 2019 Pregnancy and births per embryo transferred, own eggs & “frozen” embryo transfers

*Based on 197 embryos transferred

*Based on 114 embryos transferred

*Based on 59 embryos transferred

*HFEA states : “Redated to protect the identity of patients” – ie numbers are low in this category, typically less than 50

*HFEA states : “Redated to protect the identity of patients” – ie numbers are low in this category, typically less than 50

The information on success rates is of limited value in comparing centres and choosing where to seek treatment. If you require help with this the HFEA provide advice on choosing a clinic: www.hfea.gov.uk/choose-a-clinic/learn-about-choosing-a-clinic/

State of the art facilities


Operating from Southmead Hospital, our clinic is home to some of the most modern, cutting edge technology and lab facilities in the UK. We have an experienced and dedicated team of embryologists committed to ensuring the best success rates and highest quality of care. Our purpose-built IVF facility has helped thousands of couples to conceive and create families.

Book An Appointment

Please complete the request form below and Alex or one of the team will get back to you shortly. Alternatively, you can call us on 0117 259 1159


    Your initial consultation at BCRM is the first step in your journey towards a successful outcome.

    Find out more about what to expect from your first visit.

    Meet our expert team

    Our team of friendly, highly-skilled specialists are dedicated to providing the highest standard of patient care. We understand the emotional stress that reproductive issues can cause and we are committed to making your journey to fertility as smooth as possible.