Blastocyst culture and transfer: lessons from an unselected, difficult IVF population

Blastocyst-stage transfer has yielded excellent results in good prognosis IVF patients, but its efficacy in the general IVF population has not been clearly demonstrated. The objective of this study was to compare cleavage-stage and blastocyst-stage transfer in a mixed, general IVF population. In a prospective, quasi-randomized study, 152 patients underwent 164 treatment cycles. Patients were allocated to cleavage-stage (group 1; n = 94) or blastocyst-stage (group 2; n = 70) transfer. Main outcome measures included implantation, clinical pregnancy and live birth rates. Implantation (11.2% versus 15.5%), clinical pregnancy (34% versus 21%) and live birth rates per transfer (21.3% versus 13.8%) and per started cycle (21.3% versus 11.4%) were all comparable for groups 1 and 2, respectively. Logistic regression analysis revealed that blastocyst culture and transfer reduced the odds for pregnancy in the general IVF population and defined a good prognosis group for blastocyst transfer. Introducing blastocyst culture and transfer to all IVF patients is not advantageous. Blastocyst transfer should be offered primarily to good prognosis patients, and this group should be specifically defined in each clinical set-up.