Comparison of blastocyst transfer with day 3 embryo transfer in similar patient populations

Objective: To compare implantation and pregnancy rates (PRs) achieved with blastocyst transfer (BT) and day 3 ET in similar patient populations. Design: Retrospective analysis. Setting: Academic infertility center. Patie nt(s): One hundred consecutive patients <40 years undergoing IVF, each with more than three eight-cell embryos on day 3. Intervention(s): Patients used their own eggs for IVF or IVF and intracytop lasmic sperm injection. Embryos were cultured in P1 medium (Irvine Scientif ic, Santa Ana, CA) until day 3, when they were either transferred or, in th e case of embryos for BT, incubated in Blastocyst Medium (Irvine Scientific ), followed by transferring on day 5. Main Outcome Measure(s): Implantation and PRs. Result(s): There were no statistically significant differences in patient a ge, FSH level, or number of oocytes or zygotes. The BT group had fewer embr yos transferred (mean, 2.4) compared with the day 3-ET group (mean, 4.6). T he viable PR (cardiac activity at 6-7 weeks was considered indicative of a viable pregnancy) was higher with BT (68%, 34/50) than with day 3 ET (46%, 23/50). The implantation rate was increased with BT (47%, 56 sacs/120 embry os) compared with day 3 ET (20%, 46 sacs/231 embryos). Conclusion(s): The BT group in our study had higher implantation and PRs co mpared with the day 3-ET group. Better embryo selection, improved embryo-ut erine synchrony, and decreased cervical mucus on day 5 may have accounted f or the enhanced outcome. Out data support the use of ET to limit the number of embryos transferred while improving PRs, Fertil Steril(R) 2000;73:126-9 (C) 1999 by American Society for Reproductive Medicine.