Treating XXXX under 36 years old without top-quality embryos on day 2: a prospective study comparing double embryo transfer with single blastocyst transfer.

@entity1 @entity2099 @entity2471
BACKGROUND Embryologists currently face a challenge when counselling @entity1 regarding the stage and the number of embryos to transfer when no top-quality embryos (TQE) are available. METHODS The aim of this study was to evaluate the efficacy of single blastocyst transfer (SBT) in comparison with the transfer of two cleavage-stage embryos in @entity1 under 36 years old. A total of 450 @entity1 under 36 years undergoing their first or second IVF treatment who had no TQE on Day 2 were included in this prospective study. Couples were assigned to either a SBT or a double cleavage-stage embryo transfer ( @entity2471 ). The clinical end-points monitored were rates of implantation, delivery and multiple deliveries. RESULTS The rate of transfer was significantly lower for couples assigned to the SBT group compared with the @entity2471 group (88 versus 100%, respectively, P < 0.001) while the delivery rate per oocyte retrieval was similar in both groups (26.7%). By contrast, the rate of multiple deliveries was significantly lower in the SBT group compared with the @entity2471 group (3.3 versus 23.3%, respectively, P < 0.01). Blastocyst cryopreservation was twice as high in the SBT group compared with the @entity2471 group (39 versus 18%, respectively, P < 0.001). CONCLUSIONS These findings show the value of extended embryo culture for couples without TQE. In such situations, delaying embryo transfer in order to select a single blastocyst with the highest potential for implantation can reduce the number of @entity2099 . Furthermore, our results demonstrate that extended culture allows blastocyst cryopreservation from embryos not available for Day 2 cryopreservation.
