Transfer Strategy in an Oocyte Donation Programme

Pilot Study of the Best Transfer Strategy in an Oocyte Donation Programme: an Intention to Treat Randomized Controlled Trial

Due to the clinically and statistically significant inferior results for the D3 group following evaluation by the institutional review board.

It has been previously shown that although the activation of the embryonic genome can begin as early as two days of initiation of the embryonic development (D2), it is expressed on day 3 (D3). Without this activation, the embryo can not continue its development. Therefore, it has been suggested that extended culture to blastocyst stage could be an option to identify and better select embryos that have been able to carry out this activation. The purpose of this study is to compare cumulative pregnancy and live birth rates following transfer of cleavage embryos or blastocysts.

Intra-uterine transfer of blastocist if in cleavage embryo stage the oocyte recipient has a mínimum of 3 availables embryos with at least one of good quality to transfer and also the inta-uterine transfer of cleavage embryo (day 3) when the recipient doesn't have the previous criteria.

at 12 months after a embryo transfer (time considered enough in order to do a minimum of one frozen-thawed cycle if pregnancy is not achieved with the fresh cycle

Total number of pregnancies confirmed by ultrasound 6 weeks after embryo transfer including fresh and thawed embryos.

at 12 months after a embryo transfer (time considered enough in order to do a minimum of one frozen-thawed cycle if pregnancy is not achieved with the fresh cycle

Inclusion Criteria: Patients under their first or second cycle of a synchronous (fresh) oocyte donation cycle. Exclusion Criteria: Preimplantation genetic screening or diagnosis cycles. Patients with strict blastocyst-stage embryo transfer indication by the couple's treating physician.