SPONTANEOUS THAW CYCLES (STC)

For patients who have embryos frozen, they can call upon them if their fresh cycle fail, or after they deliver. The embryo storage needs to be renewed annually, up to a maximum of 5 years. If you do not receive our reminder but have embryos frozen in our laboratory, please contact us.

The STC is very simple, and you need to be monitored to see when you ovulate. The egg in that cycle will not be collected but you can have normal coitus to try for a pregnancy anyway. Once there is a good ovulation, your doctor will time when to replace the embryos. They will be thawed on the same morning as the ER. The ER is a simple procedure, similar to the ER you had in the fresh cycle.

If there is difficulty in having a good ovulation, your doctor may take over the cycle with hormones: cyclical steroidal replacement therapy (CSRT). The embryos will then be timed for ER at your convenience. The pregnancy rate is similar to STC. The disadvantage in this regime is that if you are pregnant you will need to continue on replacement therapy till the pregnancy is at least 10-12 weeks.

Pregnancy rates with thawed cycles was 37% per cycle in 2006 in our Centre.

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