Pregnancy outcome of day 3 versus day 5 embryo transfer: A retrospective analysis

Objective: To compare the pregnancy rate between day 3 and day 5 transfer regardless grades of embryos and number of transferred embryo. Methods: Retrospective cohort, a total of seven hundred and four patients met our inclusion criteria, with 411 had day 3 embryo transfer and 293 had day 5 embryo transfer. The patients who were older than 40 years old were excluded. Embryo transfer was carried out in all patients in both transfer groups. Results: Both clinical pregnancy rate and implantation rate did not show any statistically significant difference between the day 3 and day five transfer groups. These were 44% vs. 45% with P=0.82 and 19% vs. 19% with P=0.99 respectively. An increase of miscarriage rate with day 5 embryo transferred compare with day 3 (12.0% vs. 4.4%, P=0.01), but no significant difference was found about biochemical pregnancy rate (P=0.52). Conclusions: Transferring embryo at day 5 may not provide any additional benefit over day 3 transfers to patients. In addition, it increases the risk of miscarriage. Further studies of this issue needed for confirming our findings.