Effectiveness of 2-step (consecutive) embryo transfer. Comparison with cleavage-stage transfer

Area of Science:

• Reproductive Medicine
• Embryology
• In Vitro Fertilization (IVF)

Background:

• Conventional embryo transfer (ET) practices involve transferring cleaved embryos on day 2 post-oocyte retrieval.
• Optimizing pregnancy outcomes in assisted reproductive technologies (ART) remains a key focus.
• The viability of embryos can be better assessed at the blastocyst stage (day 5).

Purpose of the Study:

• To compare the effectiveness of a novel 2-step embryo transfer (ET) protocol against conventional day 2 ET.
• To evaluate pregnancy and implantation rates associated with the 2-step ET approach.

Main Methods:

• An observational comparative study was conducted.
• The study included patients with at least 4 embryos on day 2.
• The 2-step group (n=124) received transfer of 2 cleaved embryos on day 2 and 1 blastocyst on day 5.
• The conventional group (n=60) received transfer of 3 cleaved embryos on day 2.

Main Results:

• The 2-step ET group demonstrated a significantly higher ongoing pregnancy rate (51.6%) compared to conventional ET (26.7%) (P < .01).
• Clinical pregnancy rates were 59.7% for 2-step ET versus 30.0% for conventional ET (P < .001).
• Implantation rates were also significantly higher in the 2-step group (27.8%) versus the conventional group (11.1%) (P < .001).

Conclusions:

• The 2-step embryo transfer protocol shows superior efficacy in achieving pregnancies.
• This method may particularly benefit patients capable of producing a sufficient number of embryos for sequential transfer.
• Further research could explore patient selection criteria for this advanced ET strategy.