P-245 Cumulative live birth rates in egg donation regarding the origin of oocytes (fresh or cryopreserved oocytes) in unsynchronized cycles

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Abstract Study question Is there a difference in cumulative live birth rates between the two groups of fresh or cryopreserved donor oocytes? Summary answer In egg donation cumulative live birth rates achieved with fresh donor oocytes are similar to those with cryopreserved donor oocytes. What is known already The improvement techniques of cryopreservation of gametes and embryos with vitrification has played an important role in ART and Oocyte Donation Programs. Oocyte donation is a worldwide established method for women with premature ovarian failure, those with repeated (IVF) failure, or those who have inherited genetic abnormalities. The increasing use of Oocyte cryopreservation has improved the outcomes and the success rates. However, cryopreserved-donated oocytes have been still achieved lower live birth rates in comparison to fresh donor oocytes. Study design, size, duration This study was carried out in Assisting Nature IVF Unit from January 2015 to December 2020. 191 recipient’s cycles were examined for the cumulative live birth outcomes according to the origin of oocytes. Group A include cycles with fresh donor oocytes from the retrieval day and Group B include cycles with cryopreserved donor oocytes. Participants/materials, setting, methods 191 recipient cycles participated in the study. Group A (n = 133) received fresh donor eggs in which the formed blastocysts were cryopreserved and then were thawed for the first embryotransfer (ET). Acceptors in Group B (n = 58) received cryopreserved donor eggs and carried out a fresh embryotransfer. The rest of formed blastocysts were cryopreserved and thawed in the next ET. All acceptors transferred at most two embryos and they occurred maximum 3 embryotransfers in egg donation. Main results and the role of chance In Group A 755 fresh donor oocytes were utilized when in Group B were 269 cryopreserved oocytes. Fertilization (87% Group A, 84% Group B) and blastulation rates (70% Group A and 65% Group B) were similar between two groups. Cumulatively the live birth rate in Group A was 61% (1st ET: 51,1%, 2nd ET: 9%, 3rd ET: 0,9%). Acceptors with a failure in the first ET carried out a second ET or in the third ET with cryopreserved blastocysts. In Group B acceptors achieved 59% live birth rates (1st ET: 50%, 2nd ET: 9%). Some acceptors after the failure of the first ET carried out a second ET and delivered a healthy baby. There was not observed significant difference in live birth rate between two groups. The vitrification and warming stages in oocyte cryopreservation has been dramatically improved in recent years and therefore in our study seems to have equal live birth rates as in the fresh oocytes in egg donation program. Limitations, reasons for caution Large scale studies are required with further investigation with more equal number of studied patients between groups. Moreover, information regarding sperm quality parameters, embryos quality or endometrium should be considered. Wider implications of the findings Acceptors should be reassured that the origin of oocytes does not have impact in the likelihood of becoming pregnant. Trial registration number NONE