Abnormal implantation after fresh and frozen in vitro fertilization cycles

In autologous in vitro fertilization cycles resulting in a positive pregnancy test, fresh blastocyst embryo transfers had the lowest overall risk of abnormal implantation compared to frozen and non-blastocyst transfers.

Volume 107, Issue 5, Pages 1153–1158


Erica T. Wang, M.D., M.A.S., Anupama S.Q. Kathiresan, M.D., Catherine Bresee, M.S., Naomi Greene, M.P.H., Ph.D., Carolyn Alexander, M.D., Margareta D. Pisarska, M.D.


Fresh blastocyst transfers had the lowest overall risk of abnormal implantation but a higher risk of ectopic/heterotopic pregnancy. Although embryo cryopreservation is indicated in certain treatment cycles, elective embryo cryopreservation may not be the optimal strategy to adopt for all cycles.

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Go to the profile of Micah J Hill
about 5 years ago
Thank you for a really provocative article! For me personally, the clinical discussion of fresh versus frozen ET is one of the most relevant patient discussions I have every day. On the one hand, this data provides relief. For years we have noticed more biochemical and SAB loses in our FETs compared to our frozen. I cant think of a single clinical data point that has driven more head scratching and consternation in our practice. Switching from cryo to vit and from vaginal P to IM P has lessened this over time, but the differences still persist. So on one hand your data reassures me that this isn't an us thing, but inherent to the protocol itself. There is certainly some relief in that overall SART reporting programs experience what we do. On the other hand, the data concerns me. Because we and others have published on the negative effects of fresh transfer in regards to E2 and OB outcomes, the negative effects of fresh transfer and P and poor IVF outcomes, and the risks of fresh transfer and OHSS. So in isolation, these publications suggest freeze all FET. So the natural inclination is to say fresh transfer isn't ideal in these scenarios. But these published data don't all analyze FET outcomes under those same risk circumstances. So your data and other emerging data with FET and elevated OB risks suggest FET may not in fact be the answer. I don't feel like I have a great question to summarize this quandary I feel. I cant sort it out from the existing literature. So what are your thoughts? Is it fresh serum E, fresh serum P, the freezing protocol of slow freeze versus vit, is it assisted hatching with some freeze protocols? What do you clinically believe explains some increase pregnancy rates with FET but potentially worse downstream outcome rates with FET? I looked at our internal data with fresh versus FET data for ASRM this year. We have more pregnancies with FET, but our OB complication risk is 30% in fresh versus 50% in frozen. This is beyond your assessment of pregnancy loss. So with the rising use of freeze all for OHSS risk, elevated P, and PGD/PGS, or even just as a standard protocol practice .... this is such an important question. This study gives us valuable new data. Where do we go next to tease this out???? Would love the expert authors thoughts! And other experts on this!