Potential Benefits of FET: why more IVF patients should consider FROZEN over FRESH embryo transfer

One of the most common questions infertility patients going through Advanced Reproductive Treatments (ART) ask is: “will freezing embryos reduce my chance at a pregnancy?”  During the first decade and a half of IVF treatment, there was a much lower success rate through Frozen Embryo Transfer (FET). In a recent post, I summarized how the newer technique of “vitrification[r1] ” helped overcome the potential impact of cryotherapy upon embryo quality. And in a separate post[r2] , I described the importance of properly preparing a woman’s uterus prior to placing an embryo. Newer data is showing that due to these combined factors some patients can actually see an improvement in their pregnancy rate by deferring transfer of their embryos from a “fresh cycle” to an FET.

It has long been noted that the highest pregnancy rates are achieved when using an egg donor. Although it has often been assumed that this is due to improved embryo quality, newer data is showing that endometrial receptivity may also be a factor. The largest review to date [r3] recently combined the results of 64 clinical research studies—including 3 randomized trials. They found that freezing embryos and transferring them in a later cycle was associated with about a 30% increase in pregnancy rate. There was no difference in the rate of miscarriage; further reassuring that the process of freezing/thawing embryos maintained their health and viability.

Another important benefit of a freeze-all (or “staggered”) cycle is that it substantially reduces a woman’s risk of ovarian hyperstimulation syndrome (OHSS). So when considering your treatment options with your provider it might be worth considering the potential benefit of creating embryos now that you plan to actually transfer later.

Robert Greene, MD, FACOG


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