Blastocyst culture after repeated failure of cleavage-stage embryo transfers:: a comparison of day 5 and day 6 transfers

Objective: To evaluate the efficacy of blastocyst transfer among patients with at least three previous cleavage-stage embryo transfer failures and to compare pregnancy and implantation rates of blastocysts according to the day of embryo transfer (day 5 or day 6 after oocyte retrieval). Design: Retrospective clinical study. Setting: Private ART center. Patient(s): One hundred forty-eight patients (with at least three failed cleavage-stage embryo transfers) under-going blastocyst-stage embryo transfer. Intervention(s): Embryos were grown for up to 6 days and only blastocyst-stage (cavitating) embryos were transferred on either day 5 or day 6 after oocyte retrieval. Main Outcome Measure(s): Clinical pregnancy and implantation rates. Result(s): Blastocysts transferred on day 5 implanted almost five times the rate of those transferred on day 6 (23% vs. 5%). Pregnancy rates were triple as high among the 73 day 5 patients compared to the 63 day 6 transfer patients (38% vs. 11%). The number of blastocysts formed and per embryo rates of blastocyst formation were both significantly higher for patients undergoing day 5 transfers: more blastocysts developed (3.0 vs. 2.1) and more were transferred (3.0 vs. 1.9). In addition, blastocyst formation rates were 46% and 33%, respectively, for both groups of patients. Conclusion(s): Blastocyst transfer (preferably on day 5 after retrieval) appears to be a successful and improved alternatives for patients with multiple failed IVF attempts. Moreover, with blastocyst transfer there should be a reduction in multiple pregnancy risk, because fewer embryos have to be transferred. (C)2005 by American Society for Reproductive Medicine.