Assisted reproduction technology: Comparison of clinical outcomes between day 3 and day 5 embryo transfers

BACKGROUND: Embryo transfer (ET) is a critical step in in vitro fertilization (IVF). Selecting the day of transfer for achieving the desired outcomes has been a great challenge. AIMS AND OBJECTIVES: The aim of this study was to compare the pregnancy rates of day 3 and day 5 ET in assisted conception. MATERIALS AND METHODS: This is a longitudinal prospective study of 122 eligible patients that underwent assisted reproduction program in our facility. All patients had controlled ovarian hyperstimulation using antagonist protocol. Patients with four or more zygotes were randomly allocated on day 1 to either day 3 or 5 transfers (58 vs. 64 patients). Fertilization was achieved through conventional IVF. Zygotes were kept in a single-step medium (Global total ®) for day 3 and 5 transfers, respectively. The morphologically best two or three embryos or blastocysts were chosen for transfer in both groups. RESULTS: The overall clinical pregnancy and live birth rates for both groups were 40.2% and 33.6%. There was no statistically significant difference between day 3 and day 5 transfer regarding clinical pregnancy rates (36.2% vs. 43.8% [P = 0.51]), live birth rates (27.6% vs. 9.1% [P = 1.0]), twinning rates (18.8% vs. 20% [P = 1.0]), and rates of early pregnancy loss (8.6% versus 4.7% P = [0.2]). CONCLUSION: In this study, the clinical outcomes of blastocyst transfer are similar to day 3 ET. This underscores the need for patient selection for the choice of days of ET. Further controlled randomized prospective studies with larger sample sizes are recommended.