Embryo freeze & FET

At Repromed our scientists will freeze any good quality embryos following your fresh embryo transfer. These embryos will remain in storage until you would like them thawed and transferred, a procedure known as a frozen embryo transfer (FET). Due to higher survival rates Repromed freezes all embryos at the blastocyst stage (day 5 and/or 6) using a fast freeze technique termed vitrification.

What is vitrification?

Vitrification is an ultra rapid freeze method that bypasses ice crystal formation. Vitrification is reported to be a superior method of freezing than conventional slow freezing where survival rates range from 70-80% giving rise to increased rates in pregnancy outcome.

Frozen embryo transfer (FET)

FET stands for Frozen Embryo Transfer.  Following egg collection in an IVF cycle, the team in the lab will freeze any surplus high quality embryos.  These embryos remain frozen in storage until the woman or couple are ready to have the embryos thawed and replaced. Preparation for this, involves either ovulation monitoring of a natural cycle or a programmed cycle with the addition of estrogen and progesterone hormones. The embryo is thawed when the uterus is predicted to be at its most receptive phase for implantation. The embryo is then placed in a very fine catheter and inserted through the cervix, in a procedure which is similar to having a smear test.

Like most aspects of fertility, the likelihood of a successful pregnancy from an FET cycle is dependent on the age of the woman when her embryos were created. The graph shows the most current results from Australasian clinics and you can see that the FET cycles in blue declines at a similar rate to the Fresh embryo transfer cycles.  Frozen transfers have a higher rate of pregnancy for women over 35 years old.  This can be due to; a) the embryos are frozen when the women were slightly younger, and b) they are transferred in an unstimulated cycle where the hormone levels are more natural.

Please note that all semi-surgical procedures are carried out in affiliation with Repromed’s DAA accredited surgical unit ACSS (Auckland City Surgical Services) within the same building and using Repromed doctors.

For some women, a ‘freeze-only’ IVF cycle may be recommended if their doctor is concerned about the effect of high hormone levels on their health or uterine lining. The beauty of waiting to transfer these embryos in a thaw cycle is it gives the body time to return to a natural state when the uterus is more receptive to an implanting embryo.  Only high quality embryos are frozen and their survival rate is almost 100% which can often translate into higher pregnancy rates than fresh IVF transfers. Learn more about the benefits of a freeze-only cycle here.

And finally, FET cycles do have the benefit of requiring no injections and less blood tests. If you’d have any specific questions about FET please email .

Transferring embryos between clinics

Transferring frozen embryos between clinics is a very simple process. If you have embryos stored at a different clinic but would like treatment at Repromed please get in touch with us.