Success Rates

At EFC, our live birth rate from vitrified eggs is over 50% per embryo transfer. This rate is among the highest in the world. Our results are regularly submitted for peer-reviewed publications and have been awarded research prizes at major scientific conferences.

These results come from a prospective study of twenty-one women with an average age of thirty-two, using their own eggs, and not those of an egg donor. In this study, ten eggs were thawed and 3 embryos were used per embryo transfer.

The following should be considered when comparing the success rates of fertility centers offering egg freezing services:

Is the success rate a clinical pregnancy rate or a live birth rate?

Clinical pregnancies are early pregnancies that can be miscarried at a rate of 25%. The live birth rate is defined as the birth of at least one live infant—the desired goal of egg freezing—and is not subject to miscarriage adjustment. Thus the live birth rate per embryo transfer is the most meaningful rate of comparison.

Are the success rates per patient or per embryo transfer?

If an individual patient undergoes multiple embryo transfer procedures, she is more likely to get pregnant over time. However, each embryo transfer requires a batch of frozen eggs. To properly plan the number of eggs to freeze, you should know the pregnancy rate per embryo transfer and not the pregnancy rate per patient, which actually represents the cumulative rate based on multiple transfers.

How many embryos are being transferred per pregnancy attempt?

The more embryos transferred, the higher the chance of pregnancy. However, transferring an excessively high number of embryos (more than four) can also lead to triplets and quadruplets, which are considered high-risk pregnancies. Most leading centers in the field transfer an average of 3-4 embryos per procedure.

Are the reported pregnancy rates derived from frozen donor eggs or from the patient’s own eggs?

Pregnancy rates from donor eggs represent the highest possible rates, because the eggs come from women in their twenties. Therefore, these rates do not apply to women in their thirties or forties who are using their own eggs. To use such rates in a comparison would falsely overestimate the pregnancy rates for these groups.

How many eggs were thawed per embryo transfer?

Some facilities will thaw a large number of eggs in order to bolster pregnancy rates. When many eggs are thawed and fertilized, there are more embryos from which to choose. And while selection of high quality embryos is an important part of the process, using an unnecessary number of frozen eggs is not. This practice also results in the disposal of excess embryos, as they are unlikely to yield a pregnancy if they are frozen and thawed a second time.

Be informed about success rates. Ask the right questions.