Background: The aim of this study was to evaluate the effectiveness of the blastocyst culture method compared with the conventional day 3 transfer method using a prospective trial.
Methods: A total of 235 patients with 273 cycles were evaluated for a period of almost 1 year. Depending upon the sequence in which the ovum retrieval was performed, patients were prospectively assigned (alternate allocation) to a culture period of 3 or 5 days duration. Embryos were transferred either on day 3 (after culture in human tubal fluid) or on day 5 (after culture in sequential media).
Results: The pregnancy rates after embryo transfer on days 3 and 5 were similar at 26.5 and 25.9% respectively. Among the day 5 embryo transfer group, patients were divided into three groups corresponding to three sequential media. The pregnancy rates were 32.0% using Irvine blastocyst medium, 6.9% using G1.2/G2.2 and 32.4% using Cook blastocyst medium.
Conclusions: The results of our study were not as successful as previous studies had been. Additionally, there may have been problems in day 5 embryo transfer, such as choosing the sequential media, quality control, contamination and so on. From the results of this study, it appears that day 5 embryo transfer has no advantages for ordinary patients of assisted reproductive technology.