Pregnancy Rates in IVF

Dear Professor Brian, could you please explain what is meant by embryo transfer & blastocyst transfer? And the rates of pregnancies associated with them? Many thanks for your help.

Our Expert's Answer

This information was published 12 years, 3 months ago and was correct at the time of publication. It may not reflect our current practices or regulations.

Please note that all the answers we give are on a generic basis only, as we cannot provide more in-depth answers without access to your medical history. If you need a more detailed response, tailored to you, we would recommend a consultation with one of our Fertility Specialists for more comprehensive medical advice.

Embryo transfer is the process of putting embryos into the uterus via a catheter.  Embryo transfer can take place on day 2, day 3 or day 5 after egg collection.  A blastocyst is a stage of embryo development usually reached by day 5 or 6.  Leaving embryos until the blastocyst stage aids embryo selection but is only used when the embryo quality is good and it is difficult to choose the best embryo to transfer. The clinical pregnancy rate for all ages undergoing IVF are approximately 30% for day 2/3 transfers and 50% for blastocyst transfer.  However, it is important to understand that blastocyst transfer is not appropriate for every patient going through IVF and the results reflect a selected population of patients.