Elective cryopreservation of all embryos and subsequent cryothaw embryo transfer results in better outcomes than fresh embryo transfer in shared egg donor program

Abstract

To compare if cryopreservation of all embryos and subsequent cryothawe embryo transfer (ET) results in better outcomes compared with fresh ET in shared egg donor program and recipients. Open randomized controlled trial. From November 2012 to March 2013, 100 women from shared egg donor program that were submitted to oocyte retrieval were selected. The inclusion criteria were: age between 21 and 34 years-old, number of retrieved oocytes between 10 and 20, normal karyotype, no signs of endometriosis, no severe male factor and normal ovarian reserve. Each women shared half of their oocytes with a recipient. In the day of oocyte retrieval, the women were allocated in two groups. In group one, all the embryos were cryopreserved in day 5 and 2 blastocysts transferred in a subsequent cycle. In group two, 2 blastocysts were transferred in the same cycle. The exclusion criterion was less than two blastocysts five days after oocyte retrieval. Recipients that received fresh embryos from both groups were included as a third group. All recipients transferred 2 blastocysts in day 5. The outcomes were clinical pregnancy rate, implantation rate, miscarriage rate and multiple pregnancy rate. The comparisons among the three groups were performed two by two using chi-square test. Egg donors with fresh ET presented significantly lower clinical pregnancy rate (50%, n=47) than egg donors with frozen ET (72%, n= 50) or recipients (70.1%,n= 9; p=0.026 and 0.049, respectively). The implantation rate were also significantly lower in this group (28%) than frozen ET group (42%; p=0.042) and lower but not significantly than recipients group (39%, p=0.064). There was no differences comparing these outcomes between donors that cryopreserved embryos and recipients. No differences in miscarriage or multiple pregnancy rates was demonstrated among the groups. Three donors with fresh embryo transfer presented ovarian hyperstimulation syndrome. In shared egg donors, cryopreservation of all embryos with cryothaw transfer in subsequent cycle improves clinical pregnancy and implantation rate comparing to donors with fresh embryo transfer. In shared egg program, the policy of frozen all embryos seems to be a good choice.